Chagos Archipelago
Located near the centre of the Indian Ocean are the reefs,
banks and small islets that comprise the Chagos Archipelago. They lie 450 km south from Addu (the southernmost
atoll of the Maldives), 1,460 km southwest from Sri Lanka and 1,650 km east from the Seychelles. The islands
form the British Indian Ocean Territory (BIOT) of the United Kingdom, and except for joint US/UK military facilities
on Diego Garcia the islands are uninhabited.
The Chagos Archipelago is the southernmost group of atolls on the Laccadive-Chagos Ridge — the submarine feature upon which the Maldive and Laccadive (Lakshadweep) islands are also located. The archipelago is the youngest group of islands to be formed on the ridge, thought to have been formed by hotspot activity.
The Chagos Archipelago comprises a 500,000 km² region of the central Indian Ocean, containing a mix of
atoll formations, submerged 
banks and reefs. There are five small atolls (Blenheim Reef, Diego Garcia, Egmont Reef,
Peros Banhos and the Salomon Islands), the centrally located, mostly submerged, giant reef complex of the Great Chagos
Bank and numerous submerged reefs, shoals and banks (Benares Shoal, Cauvin Bank, Centurion Bank, Colvocoresses Reef,
Ganges Bank, Pitt Bank, Speakers Bank and Victory Bank). The banks are generally small, with the exception of the
Pitt and Speakers banks, which have areas of 1,100 km² and 800 km², respectively. The largest and most
unusual structure of the archipelago is that of the Great Chagos Bank, covering some 13,000 km². It is a largely
submerged atoll formation with just 8 small islets totalling 7 km² in area.
In all, there are around 57 islands and islets scattered among the reefs of the Chagos Archipelago with a combined land area of 63 km². The single largest landmass is that of the main island of Diego Garcia atoll, with an area of 28 km² — accounting for almost half of the total land area of the archipelago. The largest of the minor islets include: Île Aigle (2.45 km²) on the Great Chagos Bank, Île Pierre (1.5 km²) on Peros Banhos atoll, Île Sude-Est (1.5 km²) on Egmont Islands atoll, Île de Coin (1.28 km²) on Peros Banhos and Île Boddam (1.08 km²) on the Salomon Islands atoll.
Due to their isolation and current protection the reefs of the archipelago represent some of the most pristine to be found in the Indian Ocean, containing what is thought to be the Indian Ocean's highest coral reef biodiversity. The small islands provide regionally important habitats for seabirds such as the Red-footed Booby (Sula sula), Sooty Tern (Sterna fuscata), Brown Noddy (Anous stolidus), and Lesser Noddy (Anous tenuirostris), as well as important nesting beaches for the Green Turtle (Chelonia mydas) and Hawksbill Turtle (Eretmochelys imbricata).