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Similan Islands

The Similan Islands (Thai: หมู่เกาะสิมิลัน, RTGS: Mu Ko Similan, Thai pronunciation: [mùː kɔ̀ʔ si.mi.lan], Malay: Kepulauan Sembilan) is a continental archipelago in the Andaman Sea off the coast of, and part of, Phang Nga Province in southern Thailand. It is the maritime border between India and Thailand. It was established as Mu Ko Similan National Park in 1982 after a one-year assessment by the forestry department.[1]

Access and tourism

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Access to the Similan Islands is primarily through Tab Lamu Port, located just south of Khao Lak in Phang Nga Province. The park headquarters is situated in Tab Lamu, a small fishing village approximately 13 kilometres (8.1 mi) from Bang La On in Khao Lak. Regular boat services to the islands operate from the middle of October to the middle of May, with trips taking around three hours on standard boats and approximately 70 minutes by speedboat.

During the diving season, liveaboard dive boats frequent the Similan Islands. These boats, departing from Tab Lamu, Ko Lanta, Phuket, and Ranong, offer multi-day stays in the Similan National Marine Park.

The Similan Islands Park has experienced significant visitor traffic, making it one of Thailand's most overcrowded national parks. Data reported by the Department of National Parks (DNP) indicates that since October 2017, the park has received 883,438 visitors. The peak season, from mid-October to mid-May, typically sees five to six thousand visitors per day. The high visitor numbers have led to environmental degradation, prompting increased regulatory measures.[2]

Annually, the park is closed during the rainy season, from 16 May to 15 October. Specifically, the island of Ko Tachai has been indefinitely closed to tourists since 15 October 2016 to facilitate environmental recovery.[3] Following its re-opening on 15 October 2018, the park implemented a daily visitor limit of 3,850 to mitigate environmental impact.[4] This measure represents a reduction from the previous average of about 7,000 visitors per day. In 2017, the park attracted approximately 912,000 tourists. The introduction of these restrictions has elicited responses from tour operators, who express concerns over potential job losses.[5] Additionally, as part of the rehabilitation efforts, all overnight accommodations on the islands have been removed.

Geography

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Ko Similan over Ao (bay) Kuerk
Map including the Similan Islands (DMA, 1989)

The islands are at 8°39′09″N 97°38′27″E / 8.65250°N 97.64083°E / 8.65250; 97.64083

The park is an archipelago consisting of 11 islands, occupying an area of 87,500 rai ~ 140 square kilometres (54 sq mi)[6] with a land area of about 26 square kilometres (10 sq mi).[7] For convenience, the Thai Department of National Parks (DNP) has assigned numbers to the islands. From north to south, they are:[8]

  • Island 11: Ko Tachai
  • Island 10: Ko Bon, also known as Ko Talu
  • Island 9: Ko Ba-ngu, also known as Ko Bayu
  • Island 8: Ko Similan
  • Island 7: Ko Hin Pousar
  • Island 6: Ko Payu, also known as Ko Pa Yu
  • Island 5: Ko Ha
  • Island 4: Ko Miang, also known as Ko Meang. Park HQ is here.
  • Island 3: Ko Payan, also known as Ko Pa Yan
  • Island 2: Ko Payang, also known as Ko Pa Yang
  • Island 1: Ko Huyong, also known as Ko Hu Yong
A hairy-legged mountain crab, Ko Miang

The Similans lie 70 kilometres off the coast of Phang Nga Province. "Similan" is a Yawi word meaning 'nine'. Ko Bon and Tachai were added to the national park in 1998.

Ko Similan: Ko Similan is the largest island. The sea in the area has an average depth of 60 feet. Underwater it is full of rock formations and coral reefs in several shapes and forms, resembling such things as deer, leaves, brains, and mushrooms. Above the water are found many diverse species such as the Nicobar pigeon, mangrove monitor lizards, flying fox and more.

Ko Huyong: Ko Huyong has the longest and widest beach in the park. However, the park prohibits any tourists from landing on the island as the beach is a place where turtles come to lay their eggs.

Wildlife protection

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Ko Similan

Within the Similan and Surin National Parks, specific islands, namely Islands 1, 2, and 3, are restricted from public access. This measure is in place to support a turtle hatching protection program and to aid in reef conservation efforts. Notably, Island number 3 is privately owned by a member of the Thai royal family.

Although fishing activities are officially prohibited in both Similan and Surin National Parks to protect marine life and habitats, observations suggest that fishing boats frequently operate in and around these parks. Divers in the area often report encountering fishing nets entangled in the reefs and illegal fishing traps. Recent years have seen an increase in the discovery of such illegal fishing equipment, particularly in areas outside the most frequented dive sites. These traps have been found to contain a variety of marine life, including trevallies, batfish, barracuda, golden pilot jacks, and triggerfish. Notably, the regions around Ko Bon and Ko Tachai have been identified as having a higher prevalence of these fishing traps.[citation needed]

Important Bird Area

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The archipelago has been designated an Important Bird Area (IBA) by BirdLife International because it supports a population of Vulnerable pale-capped pigeons.[9]

Panorama from Similan Islands in the Andaman Sea
  • Turtle at Similan
    Turtle at Similan
  • Whale shark at Similan
    Whale shark at Similan
  • Phantom Bannerfish at Similan
    Phantom Bannerfish at Similan

2004 tsunami

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The Similan Islands were severely damaged by the 2004 Indian Ocean tsunami. Scuba divers there reported being caught in a violent, swirling current suddenly while underwater. Local camcorder footage showed the tsunami surging inland and flooding camping equipment.

Location

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See also

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References

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[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Similan Islands

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The Similan Islands, officially designated as Mu Ko Similan National Park, form an of eleven islands situated in the , approximately 70 kilometers off the western coast of in . This protected marine area, established in 1982 as Thailand's 43rd national park, spans about 140 square kilometers, including 26 square kilometers of land, and is celebrated for its boulder formations, white sandy beaches, and exceptionally rich ecosystems that support diverse marine . The name "Similan" derives from the Yawi (Malay) word for "nine," reflecting the original count of main islands—Ko Huyong, Ko Payang, Ko Payan, Ko Miang, Ko Ha, Ko Payu, Ko Similan, Ko Hin Pousar, and Ko Bangu—later expanded in 1988 to include Ko Bon and Ko Tachai. Geographically, the islands feature dramatic landscapes shaped by , with steep hills rising from waters, dense tropical forests covering the interiors, and fringing reefs that form a vibrant underwater world. The park's location between latitudes 8°28'–9°15'N and longitudes 97°–97°50'E places it in a of the , accessible primarily by boat from piers in Thap Lamu (Phang Nga) or (Phuket). Ecologically, Mu Ko Similan is a haven for , hosting over 700 of , including whale sharks, manta rays, and various sea turtles, alongside thriving coral gardens that continue to recover from past bleaching events, with over 60% rebound as of 2025. On land, the islands support more than 120 bird , such as Nicobar pigeons, and rare flora like Manilkara littoralis, all preserved through strict conservation measures. The park's global renown stems from its status as one of the world's premier and destinations, with sites like Elephant Head Rock and Christmas Point offering visibility up to 30 meters and encounters with dolphins and . To mitigate tourism impacts, access is limited to the from mid-October to mid-May, with a daily visitor cap of 3,325 people enforced since , and certain areas like Ko Tachai closed to landings for rehabilitation. These efforts underscore the park's role in sustainable and , drawing adventurers while safeguarding its fragile ecosystems against and human pressures.

Geography

Location and Extent

The Similan Islands form a continental comprising 11 granite islands in the , located approximately 70 km west of in . The group spans latitudes from 8°28' to 9°15' N and longitudes from 97° to 97°50' E, with a central position around 8°39' N, 97°38' E. The encompassing the archipelago covers a total area of 140 km², including 26 km² of land surface. Geologically, the islands consist primarily of granite outcrops that rise directly from the , formed through ancient processes along the western belt of during the period. These formations are part of the broader extending from the Thai mainland into the , which lies along the between and . The surrounding waters of the feature a steep drop-off beyond the shelf, with depths reaching up to 1,500 meters in proximity to the . The nearest access point to the mainland is Thap Lamu Port in , approximately 70 km east, which serves as the primary departure hub for vessels and influences seasonal patterns of reachability to the remote islands. This positioning underscores the Similan Islands' role within the boundaries of Mu Ko Similan National Park, emphasizing their isolation and ecological significance.

Islands and Physical Features

The Similan Islands archipelago consists of 11 islands numbered from 1 to 11, extending from south to north in the . Island 1, known as Ko Huyong, is the southernmost and smallest, featuring the longest and widest white-sand beach in the park, which serves as a key turtle nesting site. Island 4, Ko Miang, acts as the administrative center with park headquarters, visitor facilities, and two prominent white-sand beaches on its eastern side; it is the second-largest island and a hub for ranger operations. Island 8, Ko Similan, is the largest and most prominent, rising to the archipelago's highest elevation at Sail Rock, a 244-meter peak that offers panoramic views. The islands exhibit distinctive topographic features shaped by their granitic origins, including dramatic boulder-strewn western and southern shores contrasting with pristine white-sand beaches predominantly on the eastern exposures. Fringing coral reefs encircle most islands, forming shallow platforms that support diverse underwater structures. Inland areas are covered in dense tropical rainforests, with seasonal waterfalls appearing during the period, particularly on Ko Similan where feeds temporary cascades. These rainforests transition to rocky hills and peaks across the smaller islands, such as the rugged terrains of Ko Payang (Island 2), Ko Payan (Island 3), Ko Ha and Ko Hok (Islands 5 and 6), Ko Payu (Island 7), Ko Bangu (Island 9), Ko Bon (Island 10), and the northernmost Ko Tachai (Island 11), which has an 800-meter-long beach. Hydrographically, the islands lack permanent freshwater sources, relying entirely on rainwater collection for any potable water needs, with limited ecosystems confined to sheltered bays that provide minor coastal protection. Bathymetrically, the surrounding waters feature shallow fringing reefs at depths of 5 to 30 meters around the island bases, abruptly giving way to steep drop-offs descending to 40 meters or more, creating dynamic underwater ideal for marine exploration.

History

Early Exploration and Naming

The name "Similan" derives from the Yawi (a of Malay) word sembilan, meaning "nine," referring to the original count of the islands visible from the sea, though later surveys identified a total of 11 islands in the . This naming reflects the historical maritime knowledge of local communities in the region, where the islands were recognized as a group of nine prominent landforms. The Similan Islands were visited by indigenous Moken sea nomads, known as "sea gypsies," who traversed the for fishing and temporary shelter, relying on the area's rich without establishing permanent settlements due to the scarcity of freshwater sources on the islands. The , an Austronesian people with centuries-old nomadic traditions in the and nearby waters including the Andamans, used the islands seasonally as part of their seafaring lifestyle, harvesting and avoiding prolonged stays. European awareness of the Similan Islands emerged in the 19th century through British hydrographic surveys of the , which charted the as part of broader colonial mapping efforts in the . The islands remained largely isolated and unvisited by outsiders beyond occasional passage by maritime traders. In the , the islands gained attention from Western divers who explored the underwater reefs, contributing to early recognition of their ecological value.

Establishment and Development

The Mu Ko Similan was officially designated on September 1, 1982, under Thailand's National Park Act B.E. 2504 (), which provides the legal framework for establishing and managing protected areas to safeguard natural resources, with a primary focus on preserving the archipelago's rich marine ecosystems. This designation followed a one-year assessment by the Forestry Department, aiming to protect the area's coral reefs, diverse , and island formations from and environmental degradation. Early development efforts in the centered on establishing basic for park management, including initial ranger stations on Ko Miang (Island 4), which served as the primary operational hub for monitoring and enforcement activities. By the , the park administration expanded its capabilities through the addition of patrol boats to combat illegal fishing, a persistent threat to the marine habitats, while also enhancing visitor facilities such as basic bungalows on Ko Similan to support controlled growth. In 1998, the was further expanded to incorporate Ko Tachai and Ko Bon, increasing the total to 11 islands and strengthening overall ecosystem connectivity. Key policy milestones in the late 20th and early 21st centuries included considerations for international recognition. During the 2000s, the park became integrated into a broader network of Andaman Sea protected areas through initiatives like the Strengthening Andaman Marine Protected Areas Network (SAMPAN) project, launched in 2008 with support from the World Bank and WWF, to improve coordinated management and conservation across regional marine sites. Pre-tsunami developments also saw the addition of visitor centers on Ko Miang and Ko Similan in the 1990s, alongside the bungalows, which were later removed in the 2010s to facilitate habitat rehabilitation and reduce human impact.

Biodiversity

Marine Ecosystems

The marine ecosystems of the Similan Islands are defined by extensive systems that dominate the surrounding waters, creating a mosaic of underwater habitats in the . These reefs, primarily fringing types adjacent to the granite islands, encompass over 80% of the nearshore areas and support more than 200 species of hard and soft corals, including staghorn, brain, and table varieties. Notable sites like Elephant Head Rock and Point on Island 9 feature dense aggregations of these corals, with boulder-strewn slopes and crevices enhancing structural complexity. The reefs experienced a mass bleaching event in 2024 but have shown recovery, with over 60% rebounding as of 2025. A diverse array of marine fauna thrives within these coral environments, with more than 700 species recorded across the archipelago's reefs, encompassing reef-associated and pelagic forms. Prominent inhabitants include whale sharks (Rhincodon typus), manta rays (Manta birostris), and leopard sharks (Stegostoma fasciatum), which frequent cleaning stations and open channels. Sea turtles, such as hawksbill (Eretmochelys imbricata) and (Chelonia mydas) species, actively forage among the reefs for sponges, , and , despite their primary nesting occurring on adjacent beaches. Habitat variety further bolsters ecological richness, with fringing reefs transitioning into steep pinnacles and expansive boulder fields that shelter both resident and transient pelagic species. Limited beds, scattered in shallower bays, serve as critical foraging grounds for herbivorous marine life, including occasional sightings of dugongs (Dugong dugon), which rely on these meadows despite their scarcity in the region. Ecologically, the Similan Islands function as a premier in the , where converging Indian and Pacific currents promote larval dispersal among reef communities, linking them to nearby formations at Richelieu Rock and the . This connectivity sustains genetic exchange and resilience across the broader Andaman marine province.

Terrestrial Flora and Fauna

The terrestrial of the Similan Islands primarily consists of dry-evergreen forests, beach forests, and specialized plant communities on rock outcrops, reflecting the archipelago's tropical island . Dipterocarp dominate the primary dry-evergreen forests, which form the bulk of the vegetation cover, interspersed with palms and scattered mangroves such as and Bruguiera gymnorrhiza in sheltered bays. Rare plants adapted to these harsh, nutrient-poor soils include Argusia argentea, subcordata, and Manilkara littoralis, all listed among Thailand's threatened . The islands' isolation limits overall plant diversity, with no large-scale agriculture or introduced disrupting the native assemblages. Faunal diversity is modest but notable for its island-adapted species, with no large mammals present due to the remote oceanic setting; instead, 35 mammal species have been recorded, including the island flying fox (Pteropus hypomelanus) and the endemic island rat (Rattus andamanensis). Reptiles number 22 species, featuring monitor lizards (Varanus spp.) that roam the forests and beaches, alongside giant robber crabs (Birgus latro), which scavenge in coastal areas. Invertebrates exhibit high , particularly and crustaceans suited to the substrates and limited freshwater habitats like temporary pools. These pools also support amphibians, such as narrow-mouthed frogs (Microhyla spp.), underscoring the fragile, water-scarce conditions. Avifauna is a highlight, with over 90 species documented, including vulnerable endemics and residents like the (Caloenas nicobarica) and pale-capped pigeon (Columba punicea), which forage in the forest canopy. Seabirds such as the white-bellied sea-eagle (Haliaeetus leucogaster) and great-billed heron (Ardea sumatrana) are common, while migratory shorebirds seasonally utilize the sandy beaches for resting and feeding. Green sea turtles (Chelonia mydas) nest on Ko Huyong (Island 1), the primary terrestrial reptilian breeding site, with monitoring efforts recording dozens to over 100 nests annually during peak seasons.

Conservation and Protection

National Park Status and Regulations

The Similan Islands, officially designated as , were established as Thailand's 43rd on September 1, 1982, under the authority of the Department of National Parks, Wildlife and Plant Conservation (DNP), which oversees its management and protection. The park encompasses 11 islands and surrounding marine areas totaling approximately 140 square kilometers, with Ko Tachai (Island 11) annexed in 1988. To safeguard sensitive ecosystems, the park is zoned into core protected areas—particularly Islands 1 (Ko Huyong), 2 (Ko Payan), and 3 (Ko Payang)—where public entry is prohibited to protect nesting sites and reefs, alongside general use zones open for regulated visitation. Visitor access is strictly controlled to minimize environmental impact, with a daily cap of 3,850 visitors implemented upon the park's 2018 reopening, down from previous levels of around 7,000 to promote ; this includes a limit of 525 scuba divers per day. Entry requires advance permits obtained through an online e-ticketing system managed by the DNP, mandatory since October 15, 2025, for all marine national parks including Similan. Foreign adult visitors pay 500 THB, while children aged 3-14 pay 250 THB; Thai nationals pay reduced rates of 100 THB for adults and 50 THB for children, with fees collected to support conservation efforts. Key regulations emphasize ecosystem preservation, prohibiting overnight stays for general tourists since the 2018 reopening—limiting visits to day trips only—except for authorized diving operations. Additional bans include anchoring to prevent damage (vessels must use designated buoys), collecting or disturbing marine life, corals, or shells, and bringing single-use plastics such as bags, straws, and foam containers, a policy enforced across Thai national parks since 2018 with expansions in 2022. On Ko Tachai, access is restricted to and diving from boats only, with no landing permitted since its 2018 reopening to allow habitat recovery. Enforcement is handled by DNP ranger patrols stationed at key sites like Ko Miang (park headquarters) and Ko Tachai, who monitor compliance and provide mooring buoys for safe vessel attachment. The park integrates with regional frameworks as part of the Ecologically or Biologically Significant Marine Areas (EBSA) and Marine Protected Areas (MPA) networks, facilitating cross-border conservation collaboration under initiatives like the ASEAN Centre for Biodiversity.

Threats and Management Efforts

The Similan Islands face several environmental threats that endanger their rich marine biodiversity, particularly the coral reefs and associated species. Illegal , including the use of traps, has been reported in the area during the , contributing to disruption and of . Coral events triggered by El Niño phenomena have also posed significant risks; the 2010 event led to severe mortality in the , with up to 90% of corals affected in shallow waters around the Similans and nearby sites, while the 2016 event impacted approximately 50% of corals in Thai reefs, reducing live cover substantially. Pre-2018 overuse exacerbated these pressures through physical damage from anchoring, , and diving activities, leading to localized degradation. To mitigate these threats, management efforts by the Department of National Parks, Wildlife and Plant Conservation include annual closures of the park from May 15 to October 15, allowing reefs to recover during the season and reducing human impact on sensitive ecosystems. Coral restoration initiatives, such as transplantation programs, have been implemented since the mid-2010s in response to bleaching events, with ongoing monitoring through dive surveys demonstrating gradual recovery, including over 60% rebound in some affected areas. Control measures for target outbreaks, a major corallivore threat in Similan dive sites, through manual removal and population assessments, while partnerships with organizations like Reef Check Thailand support annual eco-diver-led surveys to track health across the Andaman coast. Climate change adaptation strategies address rising sea levels, which threaten nesting sites by eroding beaches and inundating habitats critical for and hawksbill turtles that nest on the islands. Research initiated in the 2020s focuses on identifying resilient coral strains in the , exploring factors like environmental variations and artificial to enhance resilience against thermal stress.

Tourism and Access

Seasonal Access and Visitor Guidelines

The Similan Islands are accessible exclusively by sea, with no roads or airports on the . The primary departure point is Thap Lamu Pier in , from where speedboats cover the approximately 60-kilometer journey in about 70 minutes, offering a quicker option for day trips. Slower ferries from the same pier take around 3 hours, providing a more economical but lengthier alternative. vessels, which accommodate multi-day diving and itineraries, typically depart from ports in Phuket or , allowing direct access without intermediate stops. The islands' operates on a strict seasonal to prioritize visitor safety amid the Andaman Sea's variable conditions and to facilitate environmental recovery during rough weather. It opens annually from October 15 to May 15, when calmer seas and better visibility prevail. For the 2025-2026 season, the park reopened on October 15, 2025, after the standard closure, enabling access under optimal conditions. Operations are weather-dependent, with cancellations possible during unexpected swells or storms to mitigate risks. Visitor guidelines emphasize safety, conservation, and minimal impact. All snorkelers must wear life jackets at all times in the water, particularly over shallow reefs, to prevent accidents and ensure buoyancy control. Strict no-touch rules apply to corals, , and seabeds, enforced to safeguard ; violations can result in fines. Post-COVID health protocols, which included mask requirements in the early , have been largely lifted by 2025, aligning with Thailand's eased national entry standards that no longer mandate proof or testing for . Daily visitor numbers are capped to manage , as outlined in broader park regulations. Supporting infrastructure includes designated mooring buoy sites across dive and anchorage areas, installed by park authorities to eliminate anchor damage to sensitive reefs. Vessels are required to use these buoys exclusively. The main visitor center on Ko Miang serves as a mandatory briefing hub, where arrivals receive orientations on rules, safety procedures, and ecological guidelines before proceeding to other islands.

Activities and Attractions

The Similan Islands offer a range of permissible recreational activities centered on their pristine marine and terrestrial environments. Scuba diving is the primary draw, with more than 30 dive sites scattered across the archipelago, featuring granite pinnacles, coral gardens, and diverse marine life such as manta rays and whale sharks. Visibility typically ranges from 20 to 40 meters during the peak season from December to April, allowing divers to explore depths up to 40 meters at sites like East of Eden and Sharkfin Reef. Snorkeling provides accessible underwater experiences at shallow reefs surrounding islands 5 through 9, including Anita's Reef and Donald Duck Bay, where visitors can observe colorful corals and fish without specialized equipment. Hiking opportunities are limited but rewarding, with short trails on Ko Similan leading to elevated viewpoints offering panoramic sea vistas. Key attractions enhance the visitor experience through natural landmarks and wildlife encounters. The iconic Sail Rock viewpoint on Island 8 rises dramatically above Bay, a sheltered white-sand ideal for relaxation and photography, providing sweeping views of the . On Ko Huyong (Island 7), restricted turtle viewing areas allow guided observations of nesting green sea turtles, emphasizing conservation during breeding seasons. The islands' dramatic granite boulder formations, sculpted by erosion, and vivid sunsets create compelling subjects for , capturing the archipelago's rugged beauty. Eco-tourism initiatives promote responsible engagement with the environment. Guided night snorkels and dives, often offered via tours, reveal bioluminescent illuminating the waters, adding a magical dimension to nocturnal explorations. Park rangers conduct educational sessions on and the islands' ecological significance, fostering awareness among tourists. These activities contribute substantially to the regional economy through dive operations, guiding services, and related expenditures. Sustainable practices are encouraged through park regulations and operator certifications, ensuring long-term viability of these attractions.

Significant Events

2004 Indian Ocean Tsunami

The 2004 , triggered by a magnitude 9.1–9.3 earthquake off the coast of on December 26, 2004, reached the Similan Islands with waves estimated at 5 to 15 meters in height. As part of Mu Ko Similan Marine National Park in Thailand's , the uninhabited archipelago experienced minimal human presence at the time, primarily limited to park rangers and occasional divers, resulting in no reported fatalities. The event was first detected in the region at the Similan Islands, approximately 70 km west of . Physical damage was most pronounced in the marine environment, where reefs suffered scouring from high-velocity currents exceeding 5 m/s, leading to breakage and dislodgement. Surveys conducted shortly after documented damaged live cover ranging from 7.2% at Beacon Reef to 39.7% at Snapper Alley Point, with an overall impact affecting approximately 13% of the reefs significantly, particularly massive and tabulate species at depths greater than 10 meters. Beaches on islands such as Ko Similan and Ko Ba-Ngu saw flooding up to one meter inland, eroding coastal sands and depositing debris that smothered beds and additional s, while campsites and ranger stations were inundated, destroying equipment and temporary structures. sites like Deep Six off Similan Island Seven were comprehensively wrecked, with sea fans and other delicate structures uprooted and doomed to drift and perish. No major infrastructural developments existed on the islands prior to , limiting broader structural losses to natural features. Immediate response efforts involved rapid assessments by Thai authorities, including surveys by the Royal Thai Navy's Hydrographic Department to evaluate coastal changes and the park's structural integrity. Joint teams from and other institutions conducted underwater inspections in January 2005, confirming the extent of reef scouring and initiating debris clearance to prevent further ecological harm. The was temporarily closed to visitors to facilitate these operations and protect recovering ecosystems, with international support from organizations like the aiding in the removal of 95% of targeted reef debris across 17 sites. In the long term, the tsunami accelerated erosion on low-lying islands like Ko Similan, exacerbating sediment transport and altering coastal profiles through ongoing sand redistribution. Some affected corals exhibited mortality within a month of the event, though partial recovery was observed in shallower areas; the disaster prompted early reviews of conservation zoning within the , leading to enhanced integrated plans and reef rehabilitation initiatives funded by entities such as the .

Recent Environmental Initiatives

Following the , Mu Ko Similan experienced an extended closure from March 2020 to October 2021, providing a critical respite for the marine ecosystem and enabling notable recovery in coral reefs and associated habitats across Thailand's marine protected areas, including the Similans. Reduced human activity led to decreased waste accumulation, improved , and higher abundances of reef-associated , as documented in assessments of 27 where tourist numbers dropped by over 90%. This period highlighted the benefits of temporary tourism halts, with park officials reporting enhanced natural resource conditions upon partial reopening. To better manage visitor impacts post-reopening, the Department of National Parks, Wildlife and Plant Conservation introduced an enhanced e-ticketing system in 2025 for Mu Ko Similan and five other southern marine parks, requiring advance online bookings with verification to cap daily entries and prevent . This digital platform, launched coinciding with the October 15, 2025, seasonal reopening after the annual closure, aims to streamline access while generating data for conservation planning; on the first day, it facilitated over 2,000 visitors. The system builds on earlier quota efforts, projecting controlled annual attendance around 100,000 to sustain reef health amid rising tourism demand. In 2025, the park launched the "Save Similan" campaign to promote eco-friendly tourism, featuring educational programs on , such as sessions on buoy usage to protect corals, a "Return Hermit Crabs to Their Homes" initiative, and the release of green sea turtles to bolster local populations. Complementing these efforts, diving teams conducted operations in November 2025 to remove abandoned fishing gear, including heavy nets and ropes from illegal sources, addressing "ghost fishing" that entangles and damages reefs. These measures align with broader goals, including enhanced patrols and partnerships for low-impact operations, amid ongoing challenges from warming seas. Annual monitoring indicates progress, with clearer waters and thriving marine sightings reported since the 2020-2021 closures.

References

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  35. https://www.tatnews.org/2022/04/thailand-imposes-a-ban-on-single-use-plastic-in-national-parks/
  36. https://www.travelfish.org/transport/thailand/southern_thailand/phang_nga/similan_islands/all
  37. https://www.rome2rio.com/s/Thap-Lamu/Similan-Islands
  38. https://thailanddiveandsail.com/similan-liveaboard/similan-liveaboard-route/
  39. https://www.nationthailand.com/life/travel/40056847
  40. https://similandivecenter.com/news/thailand-snorkeling-regulations/
  41. https://diverace.com/diving-responsibly-new-regulations-for-the-similan-islands/
  42. https://www.siam-legal.com/travel-to-thailand/the-2025-thailand-travel-requirements-all-travelers-must-meet/
  43. https://tours.co.th/similan-islands-open-15-oct-what-you-need-to-know-before-visiting/
  44. https://www.scubadiving-phuket.com/similan-islands-liveaboards/similans-dive-sites/
  45. https://www.phuket-tickets.com/similan-island-tours/donald-duck-bay/
  46. https://similan-islands.com/
  47. https://www.similandivingtours.com/blog/blogs/information/night-diving-on-similan-islands-liveaboard-diving-cruises
  48. http://www.rbrg.sc.chula.ac.th/pdf/08%20Chavanich%20et%20al%202008-Coral%20damage%20of%20Tsunami.pdf
  49. https://www.gfdrr.org/sites/default/files/publication/Tsunami%20Thailand%2C%20One%20Year%20Later%2C%20National%20Response%20and%20the%20Contribution%20of%20International%20Partners.pdf
  50. https://www.facebook.com/infoaboutthailand/posts/tsunami-2004-the-first-location-where-the-tsunami-was-noticed-was-on-the-similan/1042333511032643/
  51. https://progearthplanetsci.springeropen.com/articles/10.1186/s40645-019-0265-2
  52. https://courses.ems.psu.edu/earth107/node/676
  53. https://divehappy.com/thailand/similan-islands-after-the-tsunami/
  54. https://docs.iho.int/mtg_docs/rhc/NIOHC/NIOHC7/NIOHC7_Thailand_National_Report.pdf
  55. https://meetings.copernicus.org/www.cosis.net/abstracts/EGU2007/03283/EGU2007-J-03283.pdf
  56. https://www.ingentaconnect.com/content/cog/tme/2021/00000016/00000004/art00003
  57. https://www.bangkokpost.com/thailand/general/3013345/6-marine-parks-to-pilot-new-e-ticket-system-in-october
  58. https://aseannow.com/topic/1376188-similan-islands-reopen-with-over-2000-tourists-on-first-day/
  59. https://thailand.prd.go.th/en/content/category/detail/id/52/iid/431625
  60. https://world.thaipbs.or.th/detail/similan-islands-launch-mission-to-clear-ghost-fishing-gear/59395
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