Indian Ocean

Indian Ocean
Blue Marble Eastern Hemisphere.jpg
A composite satellite image centred on the Indian Ocean
Indian Ocean surface.jpg
The ocean-floor of the Indian Ocean is divided by spreading ridges and crisscrossed by aseismic structures
LocationIndian subcontinent, Southeast Asia, Western Asia, Northeast Africa, East Africa, Southern Africa and Australia
Coordinates20°S 80°E / 20°S 80°E / -20; 80
Max. length9,600 km (6,000 mi) (Antarctica to Bay of Bengal)[1]
Max. width7,600 km (4,700 mi) (Africa to Australia)[1]
Surface area68,556,000 km2 (26,470,000 sq mi)
Average depth3,741 m (12,274 ft)
Max. depth7,258 m (23,812 ft)
Shore length166,526 km (41,337 mi)[2]
SettlementsDurban, Mumbai, Perth, Colombo, Padang, Maputo
1 Shore length is not a well-defined measure.

The Indian Ocean is the third-largest of the world's oceanic divisions, covering 70,560,000 km2 (27,240,000 sq mi) (19.8% of the water on the Earth's surface).[4] It is bounded by Asia on the north, on the west by Africa, on the east by Australia, and on the south by the Southern Ocean or, depending on definition, by Antarctica.[5]

Scientifically, the Indian Ocean remained poorly explored before the International Indian Ocean Expedition in the early 1960s. The Challenger expedition 1872–1876 only reported from south of the polar front. The Valdivia expedition 1898–1899 made deep samples in the Indian Ocean. In the 1930s, the John Murray Expedition mainly studied shallow-water habitats. The Swedish Deep Sea Expedition 1947–1948 also sampled the Indian Ocean on its global tour and the Danish Galathea sampled deep-water fauna from Sri Lanka to South Africa on its second expedition 1950–1952. The Soviet research vessel Vityaz also did research in the Indian Ocean.[1]


A 1747 map of Africa with the Indian Ocean referred to as the Eastern Ocean
A 1658 naval map by Janssonius depicting the Indian Ocean, India and Arabia.

The Indian Ocean is named after India (Oceanus Orientalis Indicus) since at least 1515. India, then, is the Greek/Roman name for the "region of the Indus River".[6]

Called the Sindhu Mahasagara or the great sea of the Sindhu by the Ancient Indians, this ocean has been variously called Hindu Ocean, Indic Ocean, etc. in various languages. The Indian Ocean was also known earlier as the Eastern Ocean, a term was still in use during the mid-18th century (see map).[6] Conversely, when China explored the Indian Ocean in the 15th century they called it the "Western Oceans".[7]

In Ancient Greek geography the region of the Indian Ocean known to the Greeks was called the Erythraean Sea.[8]

A relatively new concept of an "Indian Ocean World" and attempts to rewrite its history has resulted in new proposed names, such as 'Asian Sea' and 'Afrasian Sea'.[9]