7 Jan 2016

The Indian Ocean Facts

indian ocean image
Indian Ocean

The Indian Ocean is the 3rd in size among all the oceans. About 20% of the total area of the World Ocean is occupied by it. The total surface area is 28,350,000 sq mi  or 73,427,000 sq km. 

It is about 4000mi (6400 km) wide at the equator but widest between the Cape Agulhas (the southernmost tip of Africa) and Australia.

The northern limits of the ocean are bounded by Iran, Pakistan, India, and Bangladesh. The eastern side of Africa is on the west cost of the ocean. Australia and Indonesia are in the eastern side. The Atlantic is to the west, the Pacific is to the east and the Antarctic Ocean is to the south of the Indian Ocean. 

Marginal Seas

indian ocean map
Map of the Indian Ocean

The Indian peninsula has divided the northern most part of the ocean into two big seas – the Arabian Sea in the west and the Bay of Bengal in the east. These two are the largest among all the marginal seas of the Indian Ocean.

There are marginal smaller seas and gulfs of the Arabian Sea, too. Major among these are the Persian Gulf, the Red Sea, Gulf of Kutch, Gulf of Khambat, and the Gulf of Eden.

The Bay of Bengal has also some smaller seas within its limits. We can mention the Andaman Sea, Malacca Srait, the Gulf of Oman, and the Gulf of Mannar among these.
There are other smaller seas and straits like the Laccadive Sea, Malacca Strait,Mozambique Channel etc


Islands of the Indian Ocean by By Nevit Dilmen [CC-BY-SA-3.0]

Madagascar is the largest among all the islands of the Indian Ocean (587041 sq km). It is an island country which was a part of the Indian subcontinent from where it was detached in 88 million years ago.

Srilanka is another large island country. It is also detached from the Indian peninsula in millions of years ago. It is considered as a part of South Asia.

Some of the important islands or archipelagos of the Indian Ocean are the Andaman and the Nicobar Islands, Laccadives, Maldives, Socotra, Mauritius, Seychelles etc.

Ridges and Trenches 

There is a large submarine ridge named as the Mid-Oceanic Ridge is extended from Asia to Antarctica. The average height of the ridge is 3000 meters or 10000 feet from the sea bottom. In some places it is high enough to form islands.

There are some trenches along the plate boundaries on the ocean floor. Diamantina and Sunda are the two deepest. At 8047 meter,  the Diamantina deep has the highest depth.


The average temperature of the water of the Indian Ocean is the highest. It reaches 28 degree centigrade (82 degrees Fahrenheit) in the Bay of Bengal. The temperature again goes up near the equator. But the water becomes ice cold near the Southern sea due to the proximity of the frozen Antarctica.

The salinity of the water varies from region to region. Due to the high evaporation rate and low rainfalls, it is highest at 37 parts per million in the Arabian Sea. In the red sea region it crosses the 40 PPM mark.

High drainage of fresh waters from the Ganges – Brahmaputra river system and other large rivers keep the salinity of the Bay of Bengal at a lower limit. It is about 31 PPM.


The water of the northern parts of the Indian Ocean is driven by the monsoon winds. The North-East Monsoon creates weak counterclockwise water current in the Arabian Sea and a clockwise strong current in the Bay of Bengal. The South-West Monsoon reverses those directions.

The southern part of the ocean’s surface currents is controlled by trade winds. So, there are regular currents here like West Australian Current, South Equatorial Current, West Wind Drift, Mozambique Current, etc.


We can divide the area of the Indian Ocean into several climate zones. In the northern part is the famous Monsoon zone. There are also Trade Wind Zone, Sub Tropical and Moderate Zone, and the Sub-Antarctic Zone.

The Monsoon Zone is the area above the 10 degrees South latitude. It is characterized by the semiannual reversing Monsoon winds. The intense heat of the south Asian summer is one of the reasons of the creation of the Monsoon winds. It brings a season of rainfall in the month of Jun to August.

The Trade Wind Zone is characterized by its regular flow of winds and unchanging wind directions. It lies between 10 to 30 degrees S. In December to June, many cyclones generate in this area, mainly near the east of Madagascar.

The 3rd Subtropical zone is situated in the Southern hemisphere. 30 to 45 degrees South is the boundary of this zone. It is controlled by light to moderate westerly winds.

The subantarctic zone is known for its low temperature. The ocean below the 45 degrees south falls in this zone. Floating ice chunks can be found here during the winter seasons.


The Indian Ocean connects with the world’s major petroleum producing regions with the major petroleum users. The petroleum from the Arab countries and from Iran goes to Europe, Americas and China via this ocean routes.

Offshore petroleum can be harnessed from the shores of Arab countries, India, Pakistan, Srilanka, Indonesia, South Africa, and Thailand. These hydrocarbon sources will run the human machines for a long time.


There are many important ports to carry out maritime trade and commerce in the Indian Ocean. Mumbai port of India opens in the Arabian Sea. Some other major ports of Indian subcontinent are Marmagao, Kolkata, Port Blair, Karachi,  Gwadar, Chennai, Tuticorin, Visakhapatnam, Paradip, Chirragong, Colombo, Galle etc.

The key to the red sea and the trading between Europe and Asia is controlled by the Aden port of Yemen. Singapore controls the trade route between Europe, South Asia, China, and Japan in the Strait of Malacca.

Mombasa, Zanzibar and Durabn are some of the major ports of the African shore of the Indian Ocean. Some other such important ports are Port Luis, Beira, Richard’s Bay, and New London etc.

There are many Asian ports beside the ocean. Some of the major ones are Muscat, Yangon, Jakarta, and Dubai etc.