Created in 1965 from Aldabra, Farquar and Desroches islands which formerly belonged to the Seychelles (these were returned to the Seychelles on independence in 1976); and the Chagos Archipelago which formerly was ruled from Mauritius when all belonged to the British Empire.

Geologically, they are the furthest south of the chain of islands which include the Maldives - the remains of a volcanic hot spot which is believed to have created the Deccan volcanic area, left behind as India moved northward.

The real importance of the colony is the atoll of Diego Garcia which is an important US base for exerting power in the Indian Ocean and Arabian Gulf area.

The inhabitants of Diego Garcia, who were the descendants of slaves from India, Africa and Madagascar, were deported to Mauritius and the Seychelles between 1968 and 1971. They conducted a court case to increase compensation or to be able to return, which was heard in July 2000. The United States presumably doesn't want them around. They are not being permitted to return. This wikipedia article may throw some light on the process by which the islanders were removed. So does this one from the New York Review of Books

US English

Nominally a British colony in the Indian Ocean, in practice a United States base.

Allegedly BIOT was provided to the US in return for US help to Britain with nuclear weapons.

The status is similar to that of Ascension Island

The island of Aldabra is the home of turtles. Proposals to make it into an air base were abandoned after protests from biologists and conservationists.

Nuclear weapons are believed to be stored at the Diego Garcia base.

This island is vulnerable to a rise in sea level from Global Warming because the average height above sea level is only about one metre.

Apparently was not seriously affected by the Indian Ocean Tsunami of 26 December 2004.

The rights of the inhabitants were ignored by the British and Americans. Some of them are trying to assert their right to return, in the British courts. There are believed to be CIA "Black Sites" on the island - secret prisons for suspected terrorists, supplied by "rendition".

One degree
Rising sea level may make the base unusable

Two degrees
Most of the land will disappear under rising sea level.