Islands of the Indian Ocean
The Indian Ocean is the Earth's third-largest body of water, with a surface area in the region of 73 million km² (including its far southern reaches, which form part of the circumpolar Southern Ocean). The Indian Ocean has a north to south span of 9,800 km from the Bay of Bengal to the coasts of Antarctica; east to west the Indian Ocean has an extent of 7,800 km, from southern Africa to the western coasts of Australia.
Around the margins of the Indian Ocean are a number of important regional and marginal seas, including: the Andaman Sea, the Arabian Sea, the Persian Gulf, and the Red Sea.
The Indian Ocean is enclosed on three sides: by the African continent in the west, by the Arabian Peninsula and southern Asia in the north and northeast, by the islands of Indonesia in the east, and by Australia in the southeast.
At high southern latitudes the waters of the Indian Ocean merge with those of both the Atlantic and the Pacific — forming a body of water known as the Southern Ocean with its northern limit defined by the 60° South line of latitude. For the purposes of this site islands found within the far southern sections of the Indian Ocean, the so-called sub-Antarctic islands, are described within the Southern Ocean section. This includes islands such as Heard Island, the Prince Edward Islands, the Îles Kerguelen, Amsterdam & St. Paul and the Crozet Islands.
Major islands found around the rim of the Indian Ocean include Madagascar (at 587,713 km² it is the fourth largest island on Earth), Socotra, Sri Lanka and the large Sunda Islands and smaller Mentawai Islands of Indonesia on its eastern extremity, the Andaman and Nicobar Islands of the northeast and the Comoros Islands of the southwest. Smaller islands around the continental margins include the Mergui Archipelago of Burma and islands such as Zanzibar and Pemba off the coast of Tanzania.
Prominent geological features of the Indian Ocean include the Laccadive-Chagos Ridge, the Mascarene Plateau and the Kerguelen Plateau. Running north to south for some 2,500 km, and extending into the central Indian Ocean, the Laccadive-Chagos Ridge is a complex submarine feature from which emerges the islands of the Lakshadweep group, the Maldives and the Chagos Archipelago. The Mascarene Plateau, in the southwestern Indian Ocean, gives rise to such islands as Mauritius, Réunion, and Rodrigues and the islands of the Seychelles group.