Mount Rinjani

Mount Rinjani (Indonesian: Gunung Rinjani; Sasak: ᬕᬸᬦ᭄ᬗᬸᬂ᭞ᬭᬶᬦ᭄ᬚᬦᬶ, romanized: gunong rinjani) is an active stratovolcano situated in regencial North Lombok of West Nusa Tenggara province on the Indonesian island of Lombok. It reaches an elevation of 3,726 metres (12,224 ft), making it the second-highest volcano in Indonesia and the highest point in the province of West Nusa Tenggara.

Adjacent to the volcano is a caldera measuring approximately 6-by-8.5-kilometre (3.7 by 5.3 mi), which contains the crater lake Sagara Anak (lit. 'Child of the Sea' (in Sasak)) — named for its striking blue coloration reminiscent of the ocean. The lake lies at an elevation of around 2,000 metres (6,600 ft) above sea level and is estimated to be about 200 metres (660 ft) deep. The caldera also features several hot springs.

Mount Rinjani and its crater lake hold significant spiritual importance for the indigenous Sasak people and certain folk religious communities, serving as sites for various religious ceremonies. In April 2018, the United Nations Educational, Scientific and Cultural Organization (UNESCO) recognized the Mount Rinjani Caldera as part of the Global Geoparks Network. Notably, the volcano's eruption in 1257 is considered one of the most powerful global volcanic events of the last 2,000 years.

Lombok is one of the Lesser Sunda Islands, a small archipelago which, from west to east, consists of Bali, Lombok, Sumbawa, Flores, Sumba and the Timor islands; all are located at the edge of the Australian continental shelf. Volcanoes in the area are formed due to the action of oceanic crusts and the movement of the shelf itself. Rinjani is one of at least 129 active volcanoes in Indonesia, four of which belong to the volcanoes of the Sunda Arc trench system forming part of the Pacific Ring of Fire – a section of fault lines stretching from the Western Hemisphere through Japan and South East Asia.

The islands of Lombok and Sumbawa lie in the central portion of the Sunda Arc. The Sunda Arc is home to some of the world's most dangerous and explosive volcanoes. The eruption of nearby Mount Tambora on Sumbawa is known for the most violent eruption in recorded history on 15 April 1815, with a scale 7 on the VEI.

The highlands are forest clad and mostly undeveloped. The lowlands are highly cultivated. Rice, soybeans, coffee, tobacco, cotton, cinnamon, cacao, cloves, cassava, corn, coconuts, copra, bananas and vanilla are the major crops grown in the fertile soils of the island. The slopes are populated by the indigenous Sasak population. There are also some basic tourist related activities established on Rinjani primarily in or about the village of Senaru.

Rinjani volcano on the island of Lombok rises to 3,726 metres (12,224 ft), second in height among Indonesian volcanoes only to Sumatra's Kerinci volcano. Rinjani has a steep-sided conical profile when viewed from the east, but the western side of the compound volcano is truncated by the 6 x 8.5 km, oval-shaped Segara Anak caldera. The western half of the caldera contains a 230-metre-deep lake whose crescentic form results from growth of the post-caldera cone Barujari at the eastern end of the caldera.

On the basis of the plate tectonics theory, Rinjani is one of the series of volcanoes built in the Lesser Sunda Islands due to the subduction of Indo-Australian oceanic crust beneath the Lesser Sunda Islands, and it is interpreted that the source of melted magma is about 165–200 kilometres (103–124 mi) depth.