Deep sea mining

Deep sea ore deposits are classified into three main types: polymetallic nodules, polymetallic sulfide deposits, and cobalt-rich crusts.^[28]: 356

Polymetallic nodules are found at depths of 4–6 km (2.5–3.7 mi) in all major oceans, though due to their metallic composition those in the Pacific Ocean are of greatest commercial interest.^[29][30] Nodules may also be found in shallow waters like the Baltic Sea and in freshwater lakes.^[31][32] They are the most readily minable type of deep sea ore.^[33] These nodules typically range in size from 4–14 cm (1.6–5.5 in) in diameter, though some can be as large as 15 cm (5.9 in).

Manganese and related hydroxides precipitate from ocean water or sediment-pore water around a nucleus, which may be a shark's tooth or a quartz grain, forming potato-shaped nodules some 4–14 cm (1.6–5.5 in) in diameter. They accrete at rates of 1–15 mm per million years.^[34] These nodules are rich in metals including rare earth elements, cobalt, nickel, copper, molybdenum, and yttrium.^[35]

The Clipperton fracture zone hosts the world's largest deposit nickel resource. These nodules sit on the seafloor and require no drilling or excavation.^[2] Nickel, cobalt, copper and manganese make up nearly 30% of the contents.^[2]

Polymetallic or sulfide deposits form in active oceanic tectonic settings such as island arcs and back-arcs and mid ocean ridge environments.^[37] These deposits are associated with hydrothermal activity and hydrothermal vents at sea depths mostly between 1 and 4 km (0.62 and 2.5 mi) and therefore located in shallower waters to other marine mineral types like polymetallic nodules. These minerals are rich in copper, gold, lead, silver and others.^[28]: 356

Polymetallic sulphides appear on seafloor massive sulfide deposits. They appear on and within the seafloor when mineralized water discharges from a hydrothermal vent. The ionic metals and sulfides in the hot, mineral-rich water precipitate upon contact with cold seawater.^[34] The stock area of the chimney structures of hydrothermal vents can be highly mineralized.

Cobalt-rich crusts (CRCs) form on sediment-free rock surfaces around oceanic seamounts, ocean plateaus, and other elevated features.^[38] The deposits are found at depths of 600–7,000 m (2,000–23,000 ft) and form 'carpets' of metal-rich layers about 30 cm (12 in) thick at the feature surface. Crusts are rich in a range of metals including cobalt, tellurium, nickel, copper, platinum, zirconium, tungsten, and rare earth elements.^[28]: 356 Temperature, depth and seawater sources shape how the formations grow.

Cobalt-rich formations exist in two categories depending on the depositional environment:^[39]

• hydrogenetic cobalt-rich ferromanganese crusts grow at 1–5 mm/Ma, but offer higher concentrations of critical metals.
• hydrothermal crusts and encrustations precipitate quickly, near 1600–1800 mm/Ma, and grow in hydrothermal fluids at approximately 200 °C (392 °F)

Submarine seamount provinces are linked to hotspots and seafloor spreading and vary in depth. They show characteristic distributions. In the Western Pacific, a study conducted at <1500 m to 3500 m bsl reported that cobalt crusts concentrate on less than 20° slopes. The high-grade cobalt crust in the Western Pacific correlated with latitude and longitude, a region within 150°E–140°W and 30°S–30°N.^[40]

Diamonds are mined from the seabed by De Beers and others.

Deep sea mining sites hold polymetallic nodules or surround active or extinct hydrothermal vents at about 3,000–6,500 meters (10,000–21,000 ft) depth.^[42][41] The vents create sulfide deposits, which collect metals such as silver, gold, copper, manganese, cobalt, and zinc.^[20][43] The deposits are mined using hydraulic pumps or bucket systems.

The largest deposits occur in the Clarion–Clipperton zone in the Pacific Ocean. It stretches over 4.5 million square kilometers of the Northern Pacific Ocean between Hawaii and Mexico.^[44] Scattered across the abyssal plain are trillions of polymetallic nodules, potato-sized rocklike deposits containing minerals such as manganese, nickel, copper, zinc, and cobalt.^[44]

The Cook Islands contains the world's fourth largest deposit in the South Penrhyn basin close to the Manihiki Plateau.^[35]

Though the nodule fields of greatest commercial interest are located in the eastern Pacific,^[29][30] polymetallic nodules are also found within the Mid-Atlantic Ridge system, around Papua New Guinea, Solomon Islands, Vanuatu, and Tonga,^[28]: 356 and the Peru Basin.^[45]

Cobalt-rich crusts are found on seamounts in the Atlantic and Indian Ocean, as well as countries such as the Pacific Federated States of Micronesia, Marshall Islands, and Kiribati.^[28]: 356

On November 10, 2020, the Chinese submersible Striver reached the bottom of the Mariana Trench 10,909 meters (35,790 feet). Chief designer Ye Cong said the seabed was abundant with resources and a "treasure map" can be made.^[46]

Promising sulfide deposits (an average of 26 parts per million) were found in the Central and Eastern Manus Basin around Papua New Guinea and the crater of Conical Seamount to the east. It offers relatively shallow water depth of 1050 m, along with a nearby gold refinery.^[43]

A 2023 study identified four regions in US territorial waters where deep sea mining would be possible: the Hawaiian Islands, the southeastern Blake Plateau, California, and the Gulf of Alaska. Hawaii has both nodules and CRCs, while the other sites hold CRCs. Each area features distinct risks. Mining Hawaii could generate plumes that could damage important fisheries and other marine life. California's waters host massive ship traffic and communication cables. Alaska waters are rich in bottom-dwelling commercially valuable sea life.^[47]

In April 2025, U.S. President Trump signed an Executive Order instructing the National Oceanic and Atmospheric Administration to expedite permits for companies to mine in both international and U.S. territorial waters, citing the Deep Seabed Hard Minerals Resource Act of 1980.^[7] This would allow mining of the deep seabed for the first time in the country.

The world's first large-scale mining of hydrothermal vent mineral deposits was carried out by Japan Oil, Gas and Metals National Corporation (JOGMEC) from August to September 2017,^[48] using the research vessel Hakurei,^[49] at the 'Izena hole/cauldron' vent field within the hydrothermally active back-arc Okinawa Trough, which contains 15 confirmed vent fields according to the InterRidge Vents Database.^[50]

The Solwara 1 Project was the first time a legitimate legal contract and framework had been developed on deep sea mining.^[51] The project was based off the coast of Papua New Guinea (PNG), near New Ireland province. The project was a joint venture between Papua New Guinea and Nautilus Minerals Inc. Nautilus Minerals held a 70% stake and Papua New Guinea purchased a 30% stake in 2011.^[52] PNG's economy relies upon the mining industry, which produces around 30–35% of GDP.^[53] Nautilus Minerals is a Canadian deep-sea mining company.^[51] The project was approved in January 2011, by PNG's Minister for Mining, John Pundari.^[51] The company leased a portion of the seabed in the Bismarck Sea.^[54] The lease licensed access to 59 square kilometers. Nautilus was allowed to mine to a depth of 1,600 meters for a period of 20 years.^[54][53] The company then began the process of gathering the materials and raising money for the project.^[55] The intent was to mine a high grade copper-gold resource from a weakly active hydrothermal vent.^[56] The target was 1.3 tons of materials, consisting of 80,000 tons of high-grade copper and 150,000 to 200,000 ounces of gold sulfide ore, over 3 years.^[53] The project was to operate at 1600 mbsl^[56] using remotely operated underwater vehicles (ROV) technology developed by UK-based Soil Machine Dynamics.^[57]

Community and environmental activists^[21] launched the Deep Sea Mining Campaign^[58] and Alliance of Solwara Warriors, comprising 20 communities in the Bismarck and Solomon Seas who attempted to ban seabed mining. Their campaign against the Solwara 1 project lasted for 9 years. Their efforts led the Australian government to ban seabed mining in the Northern Territory.^[59] In June 2019, the Alliance of Solwara Warriors wrote the PNG government calling for them to cancel all deep sea mining licenses and ban seabed mining in national waters.^[59] They claimed that PNG had no need for seabed mining due to its abundant fisheries, productive agricultural lands, and marine life.^[59] They claimed that seabed mining benefited only a small number of already wealthy people, but not local communities and Indigenous populations.^[59] Others chose to engage in more artistic forms, such as Joy Enomoto.^[60] She created a series of woodcut prints titled Nautilus the Protector. The activist community argued that authorities had not adequately addressed free, prior and informed consent for affected communities and violated the precautionary principle.^[61]

In December 2017 the company had difficulties in raising money and eventually could no longer pay what it owed to the Chinese shipyard where the "production support vessel" was docked.^[52] Nautilus lost access to the ship and equipment.^[52] In August 2019, the company filed for bankruptcy, delisted from the Toronto Stock Exchange, and was liquidated.^[62] PNG lost over $120 million dollars.^[52] Nautilus was purchased by Deep Sea Mining Finance LTD. PNG has yet to cancel the extraction license contract.

In the 1970s Shell, Rio Tinto (Kennecott) and Sumitomo conducted pilot test work, recovering over ten thousand tons of nodules in the CCZ.^[63]

Licences for mineral exploration in the area beyond national jurisdiction registered with the International Seabed Authority (ISA) are mostly located in the CCZ.^[41] As of June 2025, the ISA has entered into 17 contracts with private companies and national governments for polymetallic nodules in the CCZ, one contract with the Government of India in the Central Indian Ocean Basin (CIOB), and one contract with Chinese contractor Beijing Pioneer Hi-Tech Development Corporation in the Prime Crust Zone (PCZ) in the Western Pacific.^[45]

In 2019, the Cook Islands passed two deep sea mining laws. The Sea Bed Minerals (SBM) Act of 2019 was to enable "the effective and responsible management of the seabed minerals of the Cook Islands in a way that also...seeks to maximize the benefits of seabed minerals for present and future generations of Cook Islanders."^[64] The Sea Bed Minerals (Exploration) Regulations Act and the Sea Bed Minerals Amendment Act were enacted in 2020 and 2021, respectively.^[65]

In February 2022, the Cook Islands government Seabed Minerals Agency (SBMA) announced the award of three five-year licences exploration activities in Cook Islands EEZ to private companies Moana Minerals Limited, the Cook Islands Consortium (CIC), and Cook Islands Investment Corporation - Seabed Resources (CIIC-SR).

Moana Minerals is a subsidiary of Ocean Minerals LLC (OML), a US-based private investment firm led by President and CEO Hans Smit. Hans Smit previously led Neptune Minerals, Inc a DSM company interested in SMS exploitation in Papua New-Guinean waters. He also served as managing director of Royal IHC MMP, focused on underwater mining activities, and worked on underwater mining systems used for subsea diamond mining.^[66]

In 2023, the SBMA announced the results of a technical report on the polymetallic nodule deposit of the Cook Islands' exclusive economic zone, undertaken on its behalf by RSC Mining and Mineral Exploration. The study was based on the analysis of both historical samples from previous scientific cruises, as well as data from recent work undertaken by SBMA PMN exploration contractors CIIC-SR and Moana. RSC produced a JORC Code (2012)-compliant Mineral Resource Statement for parts of the EEZ totalling 6.7 billion tons of polymetallic nodules (wet), grading 0.44% Co, 0.21% Cu, 17.4% Fe, 15.8% Mn, and 0.37% Ni. Of this total resource, 304 million tons of nodules grading 0.5% Co, 0.15% Cu, 18.5% Fe, 15.4% Mn, and 0.25% Ni, are assessed at Indicated Resource, whereas Inferred Resources account for 6.4 billion tons grading 0.4% Co, 0.2% Cu, 17% Fe, 16% Mn, and 0.4% Ni.^[67]

In 2025, the Cook Islands announced that it had signed a five-year agreement with China focussed on exploration and research into seabed minerals.^[11]

In 2011, the Republic of Nauru sponsored an ISA exploration contract with exploration activities carried out by Nauruan company, Nauru Ocean Resources Inc (NORI).^[68] NORI is a wholly owned subsidiary of Canadian company, The Metals Company.^[69][70] Since then, The Metals Company has conducted 22 offshore research campaigns on the NORI exploration area as part of its Environmental and Social Impact Assessment.^[71] On June 29, 2021, the Republic of Nauru invoked the 'Two-Year Notice' provision of the 1994 Implementation Agreement requiring the ISA to finalize and adopt a Mining Code within two years.^[72] This two year deadline elapsed on July 9, 2023, meaning that The Metals Company and other contractors can submit an application for commercial exploitation at any time.^[73]

The Metals Company also controls two further ISA exploration licences in the CCZ through Kiribati-based Marawa Research and Exploration Ltd., and through its Tongan subsidiary Tonga Offshore Mining Limited (TOML), which it acquired from Deep Sea Mining Finance Limited in April 2020.^[74]

In April 2025, following U.S. President Donald Trump's Executive Order on offshore mining, The Metals Company submitted applications for a commercial recovery permit and two exploration licenses under the Deep Seabed Hard Mineral Resources Act and regulations set by the National Oceanic and Atmospheric Administration. The commercial recovery permit covers 25,160 square kilometers while the two exploration licence applications cover a combined 199,895 square kilometers.^[75]

In January 2024 Norway's parliament allowed multiple companies to begin submitting applications to prospect for DSM resources, mainly Seafloor Massive Sulfides (SMS), but also potentially Cobalt-rich crusts in the Norwegian EEZ, as well as on its continental shelf extension, along Mohns and Knipovich ridges Jan Mayen and Svalbard in the North Atlantic.^[76]

Norway's Institute of Marine Research recommended five to ten years of research before allowing mining. In late April 2024, the Norwegian Offshore Directorate invited interested parties to nominate blocks in this area for a first round of mineral exploration licences.^[77] First licence awards are expected for early 2025.^[78]

Three Norwegian start-up companies, Loke Marine Minerals, Green Minerals, and Adepth Minerals were expected to apply for licenses.^[79] In March 2023 Loke acquired Lockheed Martin subsidiary UK Seabed Resources Limited (UKSRL). This saw UKSRL's two PMN exploration licences in the CCZ, as well as its 19.9% stake in Ocean Minerals Singapore (OMS), an ISA contractor for PMNs in the CCZ.^[80] OMS is majority-controlled by Singaporean state-owned Keppel Offshore & Marine, now part of also Singaporean state-owned Seatrium.^[81][82]

Green Minerals is another Norwegian company which has expressed interested in mining seafloor massive sulfide (SMS) deposits in the Norwegian EEZ.^[83] In January 2023, Green Minerals signed a memorandum of understanding with the ISA to obtain an exploration licence for PMNs in the CCZ.^[84] In its May 2024 Capital Markets Day Presentation, it confirmed its ambitions to commence mining operations on SMS deposits on the Norwegian continental shelf and EEZ by 2028, as well as explore for PMNs in the CCZ in the future.^[78]

After in April 2024, the Norwegian government opened up an exploration area in the Norwegian and Greenland Seas, the World Wide Fund for Nature (WWF) declared that it would take legal action against the decision. According to the government, the seabed contains many resources including copper, zinc and cobalt, which are necessary for producing mobile phones, wind turbines, computers and batteries but as for now supplies are controlled by China or "authoritarian countries". In June the energy ministry submitted "a proposal to announce the first licensing round on the Norwegian continental shelf for public consultation." According to the government, the aim is to understand if a sustainable deep sea mining there can occur. Otherwise, "deep-sea mining would not be permitted".^[85]

Robotics and AI technologies used to selectively harvest nodules while minimizing disturbances to the deep sea environment are under development.^[86]

Remotely operated vehicles (ROVs) are used to collect mineral samples from prospective sites, using drills and other cutting tools. A mining ship or station collects the deposits for processing.^[57]

The continuous-line bucket system (CLB) is an older approach. It operates like a conveyor-belt, running from the bottom to the surface where a ship or mining platform extracts the minerals, and returns the tailings to the ocean.^[87]

Hydraulic suction mining instead lowers a pipe to the seafloor and pumps nodules up to the ship. Another pipe returns the tailings to the mining site.^[87]

Borehole Mining is used for mining of natural resources from below the seafloor.

The three stages of deep-sea mining are prospecting, exploration and exploitation. Prospecting entails searching for minerals and estimating their size, shape and value. Exploration analyses the resources, testing potential recovery and potential economic/environmental extraction impacts. Exploitation is the recovery of these resources.^[88]

Resource assessment and pilot mining are part of exploration. If successful, "resources" attain a "reserves" classification.^[89] Bottom scanning and sampling use technologies such as echo-sounders, side scan sonars, deep-towed photography, remotely operated vehicles, and autonomous underwater vehicles (AUV).

Extraction involves gathering material (mining), vertical transport, storing, offloading, transport, and metallurgical processing.

Polymetallic minerals require special treatment. Issues include spatial tailing discharges, sediment plumes, disturbance to the benthic environment, and analysis of regions affected by seafloor machines.^[89]

Deep sea mining has significant environmental impacts. Research on deep-sea polymetallic nodule mining has substantially increased in recent years, but the expected level of environmental impact is still being established.^[1] Scientists from MIT examined seafloor sediment plumes generated by a prototype mining collector in the Clarion Clipperton Zone and found that the plume forms a low-lying turbidity current which hugs the seafloor.^[90] Another MIT-led study found that modelling can reliably predict plume behaviour in the midwater column, and impact is influenced by the quantity of discharged sediment, and the turbulence of the water upon discharge.^[1]

Meta-analysis of 11 separate disturbance and test mining studies showed that impacts are often severe immediately after mining, with major negative changes in density and diversity of most groups occurring. Almost all studies show some recovery in faunal density and diversity for meiofauna and mobile megafauna, often within one year. However, very few faunal groups return to baseline or control conditions after two decades.^[91] Benchmark Mineral Intelligence, commissioned by The Metals Company, conducted a life cycle assessment of the environmental impact of producing critical minerals from polymetallic nodules in the Clarion-Clipperton Zone (CCZ). The study found that the deep-sea model performed better environmentally than traditional land-based methods, showing 54-70% lower Global Warming Potential (GWP) on average, due to renewable energy use, high metal recovery, and efficient processes.^[92] Another study in the Journal of Cleaner Production found that the production of 1 billion electric vehicles using nodules would produce 90% less CO₂ equivalent than producing the same amount of vehicles through land-based mining.^[93] While some environmental consequences (such as sediment plumes, disturbance of the bottom, and toxic effects) are known, the scientific understanding of deep sea ecosystems is currently insufficient to evaluate all possible impacts.^[20]

Technology is under development to mitigate these issues. This includes selective pick-up technology that leaves alone nodules that contain life and leaves behind some nodules to maintain the habitat.^[86]

The United Nations Environment Programme (UNEP) emphasizes the need for a comprehensive assessment of the environmental impacts of deep-sea mining, which targets polymetallic nodules at depths of 3–6.5 km (1.9–4.0 mi), polymetallic sulphides at 1–4 km (0.62–2.5 mi), and cobalt-rich ferromanganese crusts between <400 m and 3.5 km. Researchers and governments have raised significant concerns about the potential impacts on unique and fragile ecosystems, with only 24.9% of the deep seabed mapped. These ecosystems are essential for ocean and carbon cycling and are vulnerable to climate change. There are widespread calls for a moratorium on deep-sea mining until its environmental, social, and economic risks are fully investigated. The International Seabed Authority (ISA) aims to finalize exploitation regulations by 2025, and a new agreement under the UN Convention on the Law of the Sea (UNCLOS) on marine biodiversity was adopted on 19 June 2023.^[94]

Plumes are caused when seawater and sediment separated from nodules at the surface are is returned to the ocean. As the particles are fine (small and light), they can remain suspended in the water column for extended periods and spread over large areas if regenerated at the surface of the ocean. All proposed projects expect to release sediment at depths of below 2,000 meters below the Oxygen Minimum Zone. Tailings increase water turbidity (cloudiness). Plumes form wherever the tailings are released, typically either near the bottom plumes or at the surface.^[41][95] Mining-generated plumes differ significantly from traditional mining tailings, as deep-sea sediment primarily consists of naturally occurring, unprocessed material rather than chemically altered waste. Studies show that most suspended particles settle relatively quickly, with heavy sediment blanketing confined to a limited area near the source. The extent of dispersion depends on local hydrodynamics, sediment properties, and mining technology.^[1][96][97]

Near-bottom plumes occur when the sediment is pumped back down to the mining site. Depending on particle size and water currents, surface plumes can spread widely.^[41][87] In shallow water, sediment can resuspend following storms, starting another cycle of damage. In-situ studies show most seafloor sediment settles rapidly, with 90% depositing within 2 km and the vast majority within 9 km, even under extreme conditions, while heavy sediment blanketing remains confined to a small area near the source.^[1][96][97]

Disturbing or, in the case of seafloor massive sulfides and cobalt crusts, removing parts of the sea floor impacts the habitat of benthic organisms, albeit to varying degrees.^[41][97]

A study analyzing data from 11 experimental mining simulations found that deep-sea mining activities cause immediate declines in faunal density and diversity, with mobile and small-sized fauna recovering more quickly. Some ecosystems fail to return to pre-disturbance levels after 26 years, while some faunal groups partially rebound, particularly meiofauna and mobile megafauna. Due to limited testing, comparable assessments for seafloor massive sulfides (SMS) and cobalt-rich crusts remain limited.^[98][99]

Nodule fields provide hard substrate on the bottom, attracting macrofauna. A study of benthic communities in the CCZ assessed a 350 square mile area with an ROV. They reported that the area contained a diverse abyssal plain megafaunal community.^[99] Megafauna (species longer than 20 mm (0.79 in)) included glass sponges, anemones, eyeless fish, sea stars, psychropotes, amphipods, and isopods.^[99] Macrofauna (species longer than 0.5mm) were reported to have high species diversity, numbering 80 -100 per square meter. The highest species diversity was found among polymetallic nodules.^[99] In a follow-up survey in areas with potential for seabed mining, researchers identified over 1,000 species, 90% previously unknown, with over 50% dependent on polymetallic nodules for survival.^[99]

Deep sea mining generates ambient noise in normally quiet pelagic environments. However, planned operations will not use sonar and are not expected to make dangerously loud noises, with most noise highly localized and similar to that of typical marine shipping operations.^[100] Noise pollution affects deep sea fish species and marine mammals, though due to the low surface productivity of its surface waters the Clarion Clipperton Zone is unlikely to be a feeding or breeding site for large marine mammals.^[100] Impacts include behavior changes, communication difficulties, and temporary and permanent hearing damage.^[101]

Light pollution affects the environment of DSM sites as they are normally pitch dark. Mining efforts may increase light levels to illuminate the bottom. Shrimp found at hydrothermal vents suffered permanent retinal damage when exposed to submersible floodlights.^[101] Behavioral changes include vertical migration patterns, ability to communicate, and ability to detect prey.^[102]

Polymetallic nodule fields are hotspots of abundance and diversity for abyssal fauna.^[103] Sediment can clog filter-feeding organisms such as manta rays.^[95] As they block the sun, they inhibit growth of photosynthesizing organisms, including coral and phytoplankton. Phytoplankton sit at the bottom of the food chain. Reducing phytoplankton reduces food availability for all other organisms.^[41][104] Metals carried by plumes can accumulate in tissues of shellfish.^[105] This bioaccumulation works its way through the food web, impacting predators, including humans.

A recent study claimed that nodules are also important for oxygen production in the absence of light and photosynthesis. Nodules the size of potatoes have shown to be able to produce an electric current that is almost equal to the voltage in an AA-sized battery. This generate electric currents strong enough to perform electrolysis, which splits water molecules into hydrogen and oxygen.^[106][107]

One report states that biomass loss stemming from deep sea mining is estimated to be significantly smaller than that from mining on land.^[108] One estimate of land ore mining reports that it will lead to a loss of 568 megatons of biomass (approximately the same as that of the entire human population)^[109] versus 42 megatons of biomass from DSM. In addition, land ore mining will lead to a loss of 47 trillion megafauna organisms, whereas deep-sea mining is expected to lead to a loss of 3 trillion.

This kind of estimation does not take into account the recoverability of the situation: how long does nature need to reclaim an abandoned site. By contrast, a different study reported that deep sea mining would be approximately 25 times worse for biodiversity than land mining.^[110]

According to the International Union for Conservation of Nature: "Not only is deep-sea mining an energy-intensive industry with high greenhouse gas emissions, but disruption of the ocean floor, which is by far the largest carbon storage reservoir on Earth, can lead to reduced carbon sequestration as well as the release of large amounts of the potent greenhouse gas methane, exacerbating the climate crisis".^[111] However, according to the United States Geological Survey, no methane hydrates are known to exist in the Clarion Clipperton Zone where most deep-sea mining activity would take place.^[112] Also, a peer-reviewed study published in the Journal of Cleaner Production found that using nodules instead of land-ore mining can reduce CO₂ emissions by 80% (Ni), 76% (Cu), 29% (Co), and 22% (Mn).^[93]

A new insight into the complexity of the abyssal environment has been provided by a team of researchers from the Scottish Society of Marine Sciences. They have found that manganese nodules on the deep sea floor could be producing oxygen.^[107] The manganese nodules act as a kind of battery due to their composition with different metals and release oxygen into the environment. As it was previously thought that only plants and algae produce dark oxygen (oxygen produced without light), this can be seen as a scientific landslide. The research has since been subject to criticism from mining companies and independent academics who have published multiple rebuttals expressing ethical, data and methodological concerns.^[113] Researchers from the University of Gothenburg criticized the authors for "poor-quality lander incubation experiments, leading to faulty oxygen flux measurements" and as a result called for the paper to be retracted.^[114] An academic at the University of Tokyo also criticized the paper for providing no evidence for electrolysis at the seafloor and for its inconsistency with decades of prior research that failed to report oxygen production, warning in an article in Science that "there is a high probability that the paper is wrong."^[115]

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Deep-sea mining is governed by the International Seabed Authority, an autonomous international organization, established by the United Nations Convention on the Law of the Sea (UNCLOS) to oversee and regulate all mineral resource-related activities in the seabed area beyond national jurisdiction.^{[116][117][118]}

The ocean was traditionally seen as an ungoverned space, reflected in the 17th-century principle of Mare Liberum, or the freedom of the sea, proposed by Dutch jurist Hugo Grotius. Grotius argued that seas were open to all states for navigation and trade, supporting Dutch maritime expansion. However, as technology advanced and human activity in the ocean grew, tensions over governance arose. This led to the competing framework of Mare Clausum, or the closed sea, proposed by English jurist John Selden in 1635. Mare Clausum advocated for coastal state sovereignty over adjacent waters, aligning with England's goals to control trade routes and fisheries.^{[116][119][120]}

The increasing complexity of maritime use and disputes between Mare Liberum and Mare Clausum highlighted the need for a comprehensive legal framework. Early efforts, including the United Nations Conferences on the Law of the Sea (UNCLOS I in 1958 and UNCLOS II in 1960), failed due to disagreements over the balance between freedom of the seas and sovereign rights. These issues were addressed with the adoption of the United Nations Convention on the Law of the Sea (UNCLOS) on December 10, 1982, providing a universally accepted framework. Amendments to the deep seabed provisions led to the 1994 Agreement and the Part XI Implementation Agreement, which entered into force on November 16, 1994, for ratifying states, aligning with the United Nations' role and Sustainable Development Goal 14.^[121][122]

UNCLOS, comprising over 400 articles and nine annexes, is the most detailed codification of maritime law ever undertaken by states under the UN.^[122][123] Driven by complex historical debates and evolving uses of the sea, the Convention represents a compromise between freedom and territorial control.^[119] Adopted after nine years of negotiations, it was celebrated as a milestone in international law, despite challenges over provisions related to reaching a collective consensus over the seabed and areas beyond national jurisdiction.^[116]

UNCLOS created three new key institutions, playing distinct yet interrelated roles, ensuring effective governance. First, the International Tribunal for the Law of the Sea (ITLOS), functioning as an independent judicial body with the authority to resolve disputes arising from the interpretation or application of the convention.

Second, is the International Seabed Authority (ISA), an autonomous international organization that oversees and regulates all mineral resource-related activities in the seabed area beyond national jurisdiction (ISA), with a "mandate to ensure the effective protection of the marine environment from harmful effects that may arise from deep-seabed-related activities."^[118]

Third, is the Commission on the Limits of the Continental Shelf (CLCS), playing a technical and advisory role, particularly in delineating the outer limits of a state's continental shelf.

Fourth, the Meeting of States Parties (MSP), or the Meeting of States Parties to the Law of the Sea Convention (SPLOS). Convened in accordance with Article 319, paragraph 2(e) of UNCLOS (1982), the MSP serves as a forum for member states to discuss and coordinate the implementation of the convention. It holds significant administrative functions, including the election of ITLOS, and CLCS members.^{[124][125][120]}

The 20th century saw significant challenges to the free sea order, particularly regarding claims over maritime resources.^[126] In 1945, the Truman Doctrine set a precedent by asserting U.S. jurisdiction over the continental shelf's natural resources, .^[127][128] This was followed by the 1952 Santiago Declaration, where Chile, Ecuador, and Peru claimed full sovereignty over their seabed and subsoil up to 200 nautical miles, extending this sovereignty to the waters and airspace above.^[129] The wave of decolonization also led newly independent states to prioritize control over marine resources for economic development.^[116] These declarations influenced the 1982 Law of the Sea, particularly shaping the exclusive economic zone and the continental shelf's extent. This development marked a shift towards a zonal approach in international maritime law, dividing ocean spaces into distinct jurisdictional zones governed by the principles of sovereignty and freedom.^[119][126]

Under UNCLOS, states have the right and obligation to regulate activities within their coastal waters and continental shelf, structured spatially by legal zoning as follows: The Territorial Sea, extends up to 12 nautical miles from the baseline, where states can regulate laws and resources, with foreign ships granted innocent passage, including warships; the Exclusive Economic Zone stretches up to 200 nautical miles, where the state holds exclusive rights over mineral and economic resources and must preserve the environment, though it cannot restrict foreign ships. The enclosure of the EEZ marked a shift from global commons to state-controlled waters for economic and security reasons; the Extended Continental Shelf, governed by complex criteria and negotiation, allows states to claim up to 350 nautical miles beyond their continental shelf.^[128] Articles 76 to 85 of UNCLOS Part VI emphasize the importance of the continental shelf's natural resources, excluding fisheries. Notably, the Area, where the Convention designates over 50 per cent of the seabed as international jurisdiction, recognizing it as the common heritage of humankind, which entails its non-appropriation by states or private entities, its use exclusively for peaceful purposes, and benefits shared equitably.,^{[123][119][130]} Regarding Straits, Article 38 of UNCLOS ensures the right of international navigation, allowing continuous transit without coastal state interference, though states may regulate for safety and environmental protection. Additionally, the flag state holds jurisdiction over its registered ships, ensuring compliance with international laws.^[122]

The International Seabed Authority (ISA) was established under Article 156 of UNCLOS 1982 as an autonomous intergovernmental organization. Following the adoption of the implementing Agreement on July 28, 1994, and its entry into force on November 16, 1994, the ISA held its inaugural meeting in Jamaica. It gained observer status at the United Nations in October 1996, confirming its recognition as a legal entity under international law.^{[122][123][131]}

Under Article 157 of UNCLOS and the Part XI implementing agreement, the ISA is tasked with organizing and controlling activities in the Area, designated as the common heritage of mankind under Article 140 (LOSC 1982, UN 1994). This role has grown in importance with increasing interest in marine mineral exploitation by states and private entities.^[116][119] The ISA operates through three main organs: the Assembly, the council, and the Secretariat. All 168 States Parties to UNCLOS, including the EU, are members of the Assembly, which elects the Council and Secretary-General, holds the authority to approve or reject the council's proposals for seabed mining, and oversees the Authority's budget.^[132][133]

The 36-member Council authorizes contracts for seabed exploration and exploitation and proposes governance regulations subject to the Assembly's approval. It also nominates the Secretary-General, who serves a four-year term as the chief administrative officer of the ISA, supervises staff, and ensures impartiality by refraining from mining-related financial interests.^[134][135] Additional advisory bodies include the Legal and Technical Commission, which makes recommendations on mining rules, and the Finance Committee, which addresses budgetary matters. Members are nominated by states and serve in their personal capacities. The Enterprise, the Authority's commercial arm, is empowered to conduct mining operations, initially through joint ventures, to generate revenues for equitable distribution among developing nations,.^[136][137] However, critics, particularly environmental groups, argue that the ISA faces a conflict of interest as both regulator and potential operator through the Enterprise. The ISA has denied these allegations.^[138]

Article 153(2) of UNCLOS stipulates that exploration and exploitation of seabed minerals in the Area must occur under a contract with the ISA, adhering to its rules, regulations, and procedures cf. Article 162(2)(b) (UN 1982). Part XI of the Convention and the 1994 Implementation Agreement provide detailed mechanisms for ISA's administration of these contracts, ensuring compliance with international standards.^[133]

Contracts are open to both public and private enterprises sponsored by an UNCLOS State Party, provided they meet technological and financial criteria. The Council must evaluate whether economic pressures to exploit deep-sea minerals align with the need to protect marine ecosystems and biodiversity.^[135] Section 1(7) of the Annex to the 1994 Agreement requires contractors to complete preparatory work, including environmental baseline studies, impact assessments and other obligations, before exploitation. Applications must include an environmental impact assessment (EIA) and a program for oceanographic and environmental studies, with exploitation plans requiring detailed information.^[133][135] Revenues from deep-seabed mining are intended for equitable distribution for the benefit of mankind, emphasizing support for developing countries lacking resources to participate independently .^[128] To assist in its work, the ISA commissioned Massachusetts Institute of Technology in 2019 for a comparative study on various economic models to equitably share deep-sea resource revenues.^[139]

Since 1994, the ISA has authorized mining exploration contracts in the Atlantic, Pacific, and Indian Oceans, focusing on polymetallic nodules, polymetallic sulfides, and cobalt crusts found at depths of 400 to 7,000 meters.^[137] While regulations include environmental protection measures, scientists warn that mining these deposits risks irreparable harm to critical ecosystems, the ocean's carbon sink functions, and marine biodiversity.^[140]

Under the ISA licensing framework, only specific entities are eligible to conduct deep seabed mining in the Area I.^[141] According to UNCLOS, such activities are restricted to States Parties or entities, state-owned or private, nationally affiliated with or effectively controlled by these states. Sponsorship by a State Party, as required by Article 153(2)(b), is mandatory. Furthermore, Annex III, Article 4(3).^[133] specifies that private corporations must secure sponsorship from their home state, and if another state exerts effective control, its sponsorship is also required.^[142][143]

To obtain approval, States or State-sponsored entities must submit a plan of work to the ISA, which, upon approval, becomes a binding contract.^[143] This framework allows private companies to collaborate with sponsoring states, leveraging their technological resources cf. Article 162(2)(b)^[122][133] while operating under ISA's regulatory oversight.^{[122][133][143][144]} The sponsorship requirement ensures entities comply with UNCLOS obligations, as highlighted by ITLOS, binding non-state actors to international and domestic legal responsibilities, cf. Annex III, Article 4(4), and Article 139 in the convention.^[122] Sponsorship also reinforces state accountability, ensuring non-state actors operate under domestic legal systems.^[142]

Non-parties to UNCLOS and non-state actors associated with such states are excluded from deep seabed mining activities. This exclusion underscores UNCLOS's role as the prevailing legal framework for regulating seabed resource activities, with alternative regimes likely deemed inconsistent with international law.^[142][122]

UNCLOS, as amended by the 1994 Implementing Agreement, provides the legal framework for regulating activities in the Area and tasks the ISA with developing and enforcing rules, regulations, and procedures for exploring and exploiting mineral resources.^[122][123]

A contentious provision within UNCLOS, referred to as the two-year rule, established in Section 1(15) of the Annex to the 1994 Implementation Agreement,^[123] permits any Member State of ISA, who's national intends to submit a plan of work for exploitation, to request the ISA Council to complete and adopt the necessary regulatory framework within two years.^[123] If the Council fails to finalize the exploitation regulations within the prescribed period, it is nonetheless required to "consider" and "provisionally approve" the submitted application, even in the absence of a fully developed regulatory structure, cf. Section 1(15)(c) of the Annex to the 1994 Agreement on Implementation.^[123] As further prescribed in Article 162(2)(o)(ii), UNCLOS though requires the ISA Council to adopt and temporarily apply rules, regulations, and procedures for activities like prospecting, exploration, and exploitation in the seabed area. These temporary rules must then be reviewed and approved by the Assembly, as outlined in Article 160(2)(e)(ii).^[123][135]

The council's decisions on these regulations must be reached by consensus, meaning no formal objections can be raised. Unlike most Council decisions, this rule, while ensuring broad agreement, enables any single objection to block progress, potentially leading to deadlock.^[133][145] In such cases, the council is required to pursue dispute resolution, including compulsory conciliation. This requirement for consensus is crucial, hence without agreed-upon regulations, the council is not authorized to evaluate applications for exploration or exploitation, effectively stalling activities in the Area.^{[133][146][147]}

Section 1(15) offers a pathway to circumvent such deadlocks, particularly when a small group of members obstructs progress. However, this mechanism is less effective when legitimate concerns exist about the adequacy of the regulatory framework, which may require more time to ensure a precautionary and thorough approach to resource exploitation.^[135]

In June 2021, the Republic of Nauru partnered with The Metals Company to extract deep-sea minerals, driven by the need for renewable energy to support its energy sector.^[148] While deep sea mining could provide vital resources, its extraction requires significant energy and capital, and may cause environmental and social impacts on the island. Although it offers some relief, deep sea mining alone is unlikely to meet long-term demand,.^[149][150]

By July 2023, Nauru's two-year rule expired, yet UNCLOS ensures that extraction beyond national jurisdiction should benefit developing states,^{[150][151][152]} This highlights the ongoing tension and key ocean paradigms, underpinning the discussing discourse between resource access, ocean health and equitable distribution, compounded by the challenges of crafting universally binding agreements under competing interests.^[153]

Since Nauru's application in 2021, the ISA has not established a clear legal process for mining, despite efforts since 2016 to create a Mining Code. The ISA aims to adopt a new code by 2025, which will offer a stronger regulatory framework, but concerns remain about legal gaps until then.^{[154][155][156]} Critics argue for a precautionary morato-rium or ban, with support from over 900 experts,^{[140][157][158]} but experts note that issuing mining licenses is complicated until the Mining Code is finalized.^[159]

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Deep-sea mining offers significant economic potential, driven by the growing demand for critical minerals needed for green technologies such as batteries, electric vehicles (EVs), and renewable energy systems. Estimates suggest that the global economic opportunity from seabed mining could reach $20 trillion.^[160] For instance, mining 75,000 square kilometers of the seabed could generate $21–$42 billion in gross metal value over two decades.^[161][162]

Since Deep-sea mining represents a transformative $20 trillion economic opportunity to support the global energy transition. To fully realize its potential, it is essential to address challenges including significant costs, environmental risks, and regulatory uncertainties. Achieving sustainability and inclusivity in this emerging industry will require strategic investments, robust international cooperation, and effective governance mechanisms.^[162][163]

The economic viability of deep-sea mining is underpinned by the abundance of high-value resources. The Clarion-Clipperton Zone (CCZ) in the Pacific Ocean contains 3.4–5 times more cobalt and 1.8–3 times more nickel than global land-based reserves, making it a critical area for meeting future energy demands.^[163] These minerals are essential for producing low-carbon technologies, including EV batteries and renewable energy storage systems, as well as for producing steel which is widely used in infrastructure to support global development.^[163][162]

In addition to resource abundance, deep-sea mining benefits from high-grade deposits and lower operational costs compared to terrestrial mining due to reduced overburden removal. Optimizations such as reduced trench depth can cut mining time by 26% and increase deposit value by 53%.^[164] The process is also less carbon-intensive, offering both environmental and economic advantages.^[165] A study published in the Journal of Cleaner Production found that producing battery metals sufficient for the production of 1 billion electric vehicles using nodules will produce 90% less CO₂ equivalent than producing the same amount of metals through land-based mining.^[93]

From an economic perspective, deep-sea mining offers a way to diversify global mineral supply chains and reduce dependence on terrestrial mining. Nations with access to seabed resources could gain a competitive edge in securing materials essential for modern technologies.^[166] Sustainable seabed mining could also alleviate the environmental impact of land-based extraction.^[163]

Deep-sea mining presents a unique economic opportunity for developing nations, particularly small island states. Revenue from resource exploitation can provide much-needed funding for economic growth and development in vulnerable regions. The International Seabed Authority (ISA) emphasizes equitable profit sharing to ensure that economically disadvantaged nations benefit from deep-sea mining activities.^[167][163] This revenue could provide essential income for economically vulnerable island nations, helping to address global economic inequalities and foster inclusive economic growth.^[165]

Despite its promise, deep-sea mining faces economic challenges. High initial investments in technology and infrastructure, coupled with ongoing operational costs, pose barriers to entry for many nations and companies.^[162][163] The financial viability of mining operations depends on external factors such as global mineral prices and the availability of marine assets.^[164]

Environmental impacts pose long-term economic risks. Habitat destruction and the disruption of ecosystem services, including carbon cycling and biodiversity, could result in costs exceeding $465 billion in lost natural capital.^[168][163] Critics argue that these risks may outweigh the immediate financial benefits of mining operations.^[168][167]

To maximize its economic potential, deep-sea mining requires effective governance. The ISA's Mining Code aims to balance economic gains with environmental protection, ensuring sustainable and equitable practices.^[167][163] Without robust regulations, unchecked environmental degradation and inequitable profit distribution could undermine the sector's economic advantages.

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With terrestrial supplies of critical minerals dwindling, countries are seeking to diversify and secure their share of deep-sea mineral resources. As highlighted by the ISA's role in regulating these resources, the demand for seabed mining is driven by several geopolitical factors, including the rise of green technologies, a growing reliance on electronics, and heightened geopolitical tensions, particularly in Europe.^[169] According to The U.S. Department of Defense, they set a new record for sales through the foreign military sales system with more than $80 billion in sales and grant assistance, with the main buyers being countries such as Sweden, Poland and the Netherlands.^[170]

As nations like the US, Japan, and Norway push for faster exploitation of deep-sea resources, the ISA's structure becomes increasingly critical, especially as countries seek to navigate the balance between economic development and environmental sustainability. The growing focus on energy security and the economic impact of sanctions, such as those imposed on Russia due to the ongoing conflict with Ukraine, further underscores the need for reliable, alternative resource supplies like deep-sea minerals.^[171]

The global mineral market is currently dominated by China, which controls approximately 90% of the world's refined critical minerals.^[172] This dependency on China has raised concerns, particularly in the U.S., Australia, and Europe, who seek to reduce their reliance on Chinese resources. The global shift is influencing the governance model of the ISA, as countries look for more direct access to seabed minerals. By securing deep-sea mineral resources, states hope to disrupt China's monopoly and gain a stake in the emerging seabed mining market, potentially altering the geopolitical balance in mineral production and supply chains. Meanwhile, China is also trying to secure quick access to the rare materials on the deep seabed.^[173]

As seabed mining becomes a more prominent issue, new geopolitical divides are emerging within traditional alliance blocs, including among NATO members. Countries like the US, Japan, and Norway are increasingly aligned in their support for faster seabed resource extraction, driven by their need for critical minerals for green technologies. In contrast, nations such as France and Germany, concerned with environmental protection, call for stronger regulatory frameworks and a more cautious approach to seabed mining.^[174] The ISA's role in this divide is critical, as it serves as the body that governs the exploration and exploitation of these resources. The debate within the ISA mirrors broader tensions between economic growth and environmental sustainability, with different nations pushing for contrasting agendas in the regulatory framework.^[175]

The ISA's structural model is increasingly being tested by the growing demand for seabed mining resources. As countries rush to secure deep-sea minerals, the ISA's ability to manage these activities through its existing governance model is under scrutiny. Critics of the ISA point to the organization's reliance on granting exploration and exploitation licenses, which has raised concerns about the speed at which these licenses are being issued and whether adequate environmental safeguards are in place.^[176] This issue is highlighted by the differing agendas of member states, with some prioritizing economic development and others, like France and Germany, pushing for more stringent environmental regulations. As these challenges unfold, the ISA's ability to address both the economic and ecological aspects of deep-sea mining becomes a central issue in global resource governance.

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Deep-sea mining focuses on three primary sources of minerals: polymetallic nodules, The IEA (2022)^[177] projects that the clean energy sector will increasingly dominate the demand for metals like copper, nickel, cobalt, rare-earth elements, and lithium. This surge is expected to accelerate over the next two decades, with lithium demand growing particularly fast. This rising demand, alongside limited terrestrial resources, is fueling interest in deep-sea mining as a potential source of these critical materials.^[178] The International Energy Agency (IEA, 2022) predicts that the clean energy sector will significantly increase its share of demand for critical raw materials (CRMs) in the coming decades. By 2040, demand for lithium is expected to grow more than 40 times, while demand for graphite, cobalt, and nickel will increase by 20-25 times. This growing demand raises concerns about the availability of CRMs, which are also vital to industries like information technology and defense. The European Commission continues to monitor supply risks for these materials (EC 2020c, 2023).

Future trends in deep-sea mining are increasingly linked to the potential for recycling critical raw materials (CRM). Recycling could address rising demand, particularly in Europe, where the supply of CRMs like cobalt, nickel, and lithium is crucial for clean energy technologies. By 2050, recycling could meet up to 77% of Europe's metal needs.^[179] However, challenges in recycling capacity, collection, and sorting must be addressed. Regulatory frameworks are evolving, with new rules on minimum recycling rates for battery metals, aiming to support this transition.^[180]

Future trends in deep-sea mining are heavily influenced by technological advancements and fluctuating demand for critical materials. While projections for nickel demand by 2050 vary significantly—from 24 to 100 million tones^[181] emerging innovations, such as lithium-sulfur and sodium-ion batteries, could reduce reliance on certain minerals like nickel and cobalt. The ISA (2022)^[182] forecasts that, by 2035, deep-sea mining could yield up to 36 million tons of nodules annually, meeting a significant portion of global manganese, nickel, and cobalt demand. However, market volatility and advances in recycling could alter the feasibility of these operations.

In the 1960s, the prospect of deep-sea mining was assessed in J. L. Mero's Mineral Resources of the Sea.^[43] Nations including France, Germany and the United States dispatched research vessels in search of deposits. Initial estimates of DSM viability were exaggerated. Depressed metal prices led to the near abandonment of nodule mining by 1982. From the 1960s to 1984 an estimated US$650 million was spent on the venture, with little to no return.^[43]

A 2018 article argued that "the 'new global gold rush' of deep sea mining shares many features with past resource scrambles – including a general disregard for environmental and social impacts, and the marginalisation of indigenous peoples and their rights".^[183][184]

• In 2001, China Ocean Mineral Resources Research and Development Association (COMRA), received China's first exploration license.^[6]

In December 2023, the research vessel MV Coco was disrupted by Greenpeace activists blocking the collection of data to support a mining permit.^[210] Obstructing canoes and dinghies were countered by water hoses. The mining ship was conducting research for The Metals Company.^[210] The vessel MV Coco is owned by Magellan.^[211]

BMW pledged not to use DSM materials in its cars. In October 2023, the UK joined Canada and New Zealand in calling for a moratorium.^[83] In the beginning of August 2024, 32 countries were against the immediate commencement of deep sea mining.^[212]

The environmental organization "The Oxygen Project" generally proposes, as an alternative to deep sea mining, "system change to sustainable alternative economic models that don't require infinite resource extraction from our environment".^[213] The Environmental Justice Foundation and Greenpeace proposed circular economy, public transport, and less car dependency, energy efficiency and resource efficiency.^[214][215]

• Seabed mining – Extracting minerals from the seabed
• Blue economy – Economy based on exploitation and preservation of the marine environment
• Blue justice
• Copper mining in the Democratic Republic of the Congo
• Deepsea mining in Namibia
• Deepwater drilling – Using a drilling rig to bore holes for petroleum extraction in deep sea
• Human impact on marine life
• Ocean colonization – Type of ocean claim
• Ocean development – Establishing of human activities at sea and use of the ocean

• United Nations Convention on the Law of the Sea (PDF). United Nations. 10 December 1982.