ropical cyclones occur during May/June and October/November in
the north Indian Ocean and January/February in the south Indian Ocean

Terrain: surface dominated by counterclockwise gyre (broad, circular
system of currents) in the south Indian Ocean; unique reversal of surface
currents in the north Indian Ocean--low pressure over southwest Asia from hot,
rising, summer air results in the southwest monsoon and southwest-to-northeast
winds and currents, while high pressure over northern Asia from cold, falling,
winter air results in the northeast monsoon and northeast-to-southwest winds
and currents; ocean floor is dominated by the Mid-Indian Ocean Ridge and
subdivided by the Southeast Indian Ocean Ridge, Southwest Indian Ocean Ridge,
and Ninety East Ridge; maximum depth is 7,258 meters in the Java Trench

Natural resources: oil and gas fields, fish, shrimp, sand and
gravel aggregates, placer deposits, polymetallic nodules

Environment: endangered marine species include the dugong, seals,
turtles, and whales; oil pollution in the Arabian Sea, Persian Gulf, and
Red Sea

Note: major choke points include Bab el Mandeb, Strait of Hormuz,
Strait of Malacca, southern access to the Suez Canal, and the Lombok Strait;
ships subject to superstructure icing in extreme south near Antarctica from
May to October

- Economy
Overview: The Indian Ocean provides a major transportation highway
for the movement of petroleum products from the Middle East to Europe
and North and South American countries. Fish from the ocean are of growing
economic importance to many of the bordering countries as a source of both food
and exports. Fishing fleets from the USSR, Japan, Korea, and Taiwan also exploit
the Indian Ocean for mostly shrimp and tuna. Large reserves of hydrocarbons are
being tapped in the offshore areas of Saudi Arabia, Iran, India, and Western
Australia. An estimated 40% of the world's offshore oil production comes from
the Indian Ocean. Beach sands rich in heavy minerals and offshore placer
deposits are actively exploited by bordering countries, particularly India,
South Africa, Indonesia, Sri Lanka, and Thailand.

Industries: based on exploitation of natural resources, particularly
marine life, minerals, oil and gas production, fishing, sand and gravel
aggregates, placer deposits

- Communications
Ports: Bombay (India), Calcutta (India), Madras (India),
Colombo (Sri Lanka), Durban (South Africa), Fremantle (Australia),
Jakarta