The Andaman Sea

The Andaman Sea (Burmese: မုတ္တမ; IPA: [moʊʔtəma̰]) is a body of water to the southeast of the Bay of Bengal, south of Myanmar, west of Thailand and east of the Andaman Islands; it is part of the Indian Ocean. It is roughly 1200 kilometres long (north-south) and 650 kilometres wide (east-west), with an area of 797,700 km². Its average depth is 870 meters, and the maximum depth is 3,777 meters.
At its southeastern reaches, the Andaman Sea narrows to form the Straits of Malacca, which separate the Malay Peninsula from the island of Sumatra.

Ocean floor tectonics
Running in a rough north-south line on the seabed of the Andaman Sea is the boundary between two tectonic plates, the Burma plate and the Sunda Plate. These plates (or microplates) are believed to have formerly been part of the larger Eurasian Plate, but were formed when transform fault activity intensified as the Indian Plate began its substantive collision with the Eurasian continent.
As a result, a seafloor spreading centre was created, which began to form the marginal basin which would become the Andaman Sea, the current stages of which commenced approximately 3-4 million years ago (Ma).

Volcanic activity
Within the sea to the east of the main Great Andaman island group is Barren Island, an active volcano (the only presently active volcano associated with the Indian subcontinent). Its volcanic activity is due to the ongoing subduction of the India Plate beneath the Andaman island arc, which forces magma to rise in this location of the Burma Plate. The volcanic island of Narcondam which lies further to the north was also formed by this process; however it has not recently been active.

The Andaman Islands are a group of islands in the Bay of Bengal, and are part of the Andaman and Nicobar Islands Union Territory of India. Port Blair is the chief community on the islands, and the administrative centre of the Union Territory. The Andaman Islands form a single administrative district within the Union Territory, the Andaman district (the Nicobar district was separated and established as a new district in 1974). The population of the Andamans was 314,084 in 2001.

Physical geography
There are 576 islands in the group, 26 of which are inhabited. They are located 950km from the mouth of the Hooghly River, 193 km from Cape Negrais in Myanmar (the nearest point of the mainland), and 547 km from the northern extremity of Sumatra. The length of the island chain is 352 km and its greatest width is 51 km. The total land area of the Andamans is 6408 km².
The five chief islands, spread over a distance of 251 km, are known collectively as Great Andaman. The individual islands are, in order from north to south: North Andaman, Middle Andaman, South Andaman, Baratang and Rutland Island. Four narrow straits separate these islands: Austin Strait, between North and Middle Andaman, Homfray's Strait between Middle Andaman, Baratang, and the north extremity of South Andaman; Middle (or Andaman) Strait between Baratang and South Andaman and Macpherson Strait between South Andaman and Rutland Island. Of these only the last is navigable by ocean-going vessels.
Together with the chief islands are, on the extreme north, the Landfall Islands, separated by the navigable Cleugh Passage; Interview Island, separated by the navigable Interview Passage, off the West coast of Middle Andaman; Labyrinth Island off the southwest coast of South Andaman, through which is the navigable Elphinstone Passage; Ritchie's (or the Andaman) Archipelago off the East coast of South Andaman and Baratang, separated by the wide and safe Diligent Strait and intersected by Kwangtung Strait and the Tadma Juru (Strait). Little Andaman, roughly 42 km by 26 km, forms the southern extremity of the whole group and lies 50 km south of Rutland Island across the Manners Strait, the main shipping route between the Andamans and the Madras coast. Besides these are a great number of islets lying off the shores of the main islands.
The principal outlying islands include the North Sentinel, a dangerous island of about 73 km², lying about 29 km off the west coast of the South Andaman. North Sentinel is inhabited by one of the most isolated peoples on earth, the Sentinelese, who resist any contact with outsiders. About 29 km west of the Andamans are the dangerous Western Banks and Dalrymple Bank, rising to within a few metres of the surface of the sea and forming, with the two Sentinel Islands, the tops of a line of submarine hills parallel to the Andamans.
The Andamans is the only place in India with an active volcano. Barren Island, northeast of Port Blair, became active in 1990s after being quiescent for almost two hundred years. It erupted again in May 2005, with experts pointing to the post-tsunami change in tectonic plates as the likely cause. The isolated extinct volcano of Narcondam, rising 710 m out of the sea, is 114 km east of North Andaman. Plans are afoot to stimulate tourism to the volcanoes in the area. Also 64 km to the east is the Invisible Bank, with one rock just awash, and 55 km southeast of Narcondam is a submarine hill rising to 689 m below the surface of the sea. Narcondam, Barren Island and the Invisible Bank, a great danger of these seas, are in a line almost parallel to the Andamans inclining towards them from north to south.

Climate
The climate is typical of tropical islands of similar latitude. It is always warm, but with sea-breezes. Rainfall is irregular, but usually dry during the north-east, and very wet during the south-west, monsoons.

People
Main article: Andamanese
The Andamanese is a collective term to describe the peoples who are the aboriginal inhabitants of the Andaman Islands and Nicobar Islands, located in the Bay of Bengal. The term includes the Great Andamanese, Jarawa, Onge, Sentinelese and the extinct Jangil. Anthropologically they are usually classified as Negritos, represented also by the Semang of Malaysia and the Aeta of the Philippines.
For information on the indigenous languages, see Andamanese languages.