Indian Ocean is the third largest ocean (73,427,000 sq
km), extending from South Asia to Antarctica and from
East Africa to South East Australia. It is 6,400 km wide
at the equator. It constitutes about 20% of the world's
total ocean area.
The Indian Ocean is connected with the Pacific Ocean by
passages through the Malay Archipelago and between
Australia and Antarctica; and with the Atlantic Ocean by
the expanse between Africa and Antarctica and by the
Suez Canal. Its chief arms are the Arabian Sea (with the
Red Sea, the Gulf of Aden, and the Persian Gulf), the
Bay of Bengal, and the Andaman Sea.
The continental shelf of the Indian Ocean is narrow.
Madagascar and Sri Lanka, the largest islands in the
ocean, are structurally parts of the continents as are
Socotra, the Andaman Islands, and the Nicobar Islands;
the Seychelles and the Kerguelen Islands are exposed
tops of submerged ridges.
The Laccadives, the Maldives, and the Chagos are low
coral islands, and Mauritius and Réunion are high
volcanic cones. The floor of the Indian Ocean has an
average depth of c.11,000 ft (3,400 m). The greatest
depth (25,344 ft/7,725 m) is in the Java Trench, South
of Java, Indonesia.
The Indian Ocean receives the waters of the Zambezi,
Tigris-Euphrates, Indus, Ganges-Brahmaputra, and
Irrawady rivers. The surface waters of the ocean are
generally warm, although close to Antarctica pack ice
and icebergs are found.
The southwest monsoon draws moisture from the Indian
Ocean and drops heavy rainfall on the Indian
subcontinent and Southeast Asia. The Indian Ocean has
two water circulation systems - a regular
counterclockwise southern system (South Equatorial
Current, Mozambique Current, West Wind Drift, West
Australian Current) and a northern system, the Monsoon
Drift, whose currents are directly related to the
seasonal shift of monsoon winds.