The Great Chagos Bank, in the Chagos Archipelago, about 500 km South of the Maldives, is the largest atoll structure in the world, with a total area of roughly 13 000 km². There are seven or eight individual islands on the rim of the atoll, one in the North (Nelson's Island) and the others on the Eastern rim. The total land area of the islands is about 4.5 km². The Atoll is administered by Mauritius.

The individual islands, starting in the South clockwise, are:

• Danger Island (slightly more than 2 km long from North to South, up 1 km wide, land area 0.66 km², vegetated with palm trees up to 12 m high, Strict Nature Reserve since 1998)

• Eagle Islands
  • Ile Aigle (Eagle Island, vegetated with high coconut trees, land area 2.45 km²
  • Cow Island (Ile aux Vaches, vegetated with trees, land area 0.2 km², Strict Nature Reserve since 1998)
  • according to some sources, there is a third island in this group

• Three Brothers (Trois Fréres) and Resurgent Islands (vegetated with high coconut trees, land area 0.4 km², Strict Nature Reserve since 1998)
  • Ile du Sud (South Island, largest of the group), 0.23 km²
  • Ile du Mileu (Middle Island), 0.08 km²
  • unnamed rocky islet
  • Ile du Nord (North Island), 0.06 km²

• Nelsons Island (2 km long from East to West, up to 1 km wide, land area 0.81 km², 3 m high, bushy vegetation, Strict Nature Reserve since 1998)

Nature reserves | Indian Ocean atolls