Geography
Indian Ocean
Area
total
70.56 million sq km
Climate
northeast monsoon (December to April), southwest monsoon (June to October); tropical cyclones occur in May/June and October/November within the northern Indian Ocean, and in January/February in the southern Indian Ocean
Location
the expanse of water situated among Africa, the Southern Ocean, Asia, and Australia
Coastline
66,526 km
Elevation
mean depth
-3,741 m
ocean zones
the ocean is categorized into three distinct zones depending on depth and light conditions; under ideal circumstances, sunlight can penetrate approximately 1,000 m into the ocean, although significant light is rarely found below 200 m
euphotic zone: the upper 200 m (656 ft), referred to as the "sunlight" zone; minimal light penetrates beyond this level
dysphotic zone: spans from 200 m (656 ft) to 1,000 m (3,280 ft), known as the twilight zone; light intensity declines swiftly with increasing depth, making photosynthesis unfeasible
aphotic zone: located beneath 1,000 m (3,280 ft), commonly called the midnight zone; sunlight does not reach these depths
lowest point
Java Trench -7,192 m unnamed deep
highest point
sea level
Bathymetry
atolls
the following are examples of atolls in the Indian Ocean (see Figure 2):
Bassas da India
Chagos Archipelago/Diego Garcia
Europa Island
Juan de Nova Island
Lakshadweep Islands
Maldive Islands
Seychelles
abyssal plains
the following are examples of features on the abyssal plains of the Indian Ocean (see Figure 2):
Arabian Basin
Crozet Basin
Madagascar Basin
Mid-Indian Basin
Mozambique Basin
Wharton Basin
ocean trenches
the following are examples of ocean trenches on the floor of the Indian Ocean (see Figure 2):
Java/Sunda Trench (deepest point in the Indian Ocean)
mid-ocean ridge
the following are examples of mid-ocean ridges on the floor of the Indian Ocean (see Figure 2):
Central Indian Ridge
Davie Ridge
Southeast Indian Ridge
Southwest Indian Ridge
continental shelf
the following are examples of features on the continental shelf of the Indian Ocean (see Figure 2):
Exmouth Plateau
Indus Canyon
The Swatch of No Ground/Ganges Canyon (Bay of Bengal)
Sunda Shelf
continental slope
the following are examples of features on the continental slope of the Indian Ocean (see Figure 2):
Bengal Fan
Indus Fan
undersea terrain features
the following are examples of undersea terrain features on the floor of the Indian Ocean (see Figure 2):
Andaman-Nicobar Ridge
Chagos-Laccadive Ridge
Kerguelen Plateau
Madagascar Plateau
Mascarene Plateau
Mozambique Plateau
Ninetyeast Ridge
Ocean volume
ocean volume
264 million cu km
percent of World Ocean total volume
19.8%
Natural hazards
intermittent icebergs represent a navigational risk in the southern regions
Geography - note
key chokepoints include Bab el Mandeb, Strait of Hormuz, Strait of Malacca, southern entry to the Suez Canal, and the Lombok Strait
Natural resources
resources such as oil and gas fields, fish, shrimp, sand and gravel aggregates, placer deposits, and polymetallic nodules
Area - comparative
nearly seven times larger than the United States
Major ocean currents
the counterclockwise Indian Ocean Gyre consists of the southward flowing warm Agulhas and East Madagascar Currents to the west, the eastward flowing South Indian Current to the south, the northward flowing cold West Australian Current to the east, and the westward flowing South Equatorial Current to the north; a notable annual shift in surface currents occurs in the northern Indian Ocean; low atmospheric pressure over southwest Asia due to hot, ascending summer air leads to the southwest monsoon and southwest-to-northeast winds along with clockwise currents, while high pressure over northern Asia caused by cold, descending winter air results in the northeast monsoon and northeast-to-southwest winds along with counterclockwise currents
Geographic coordinates
20 00 S, 80 00 E