There are four oceans on the earth. They are all inter-connected. In order of size they are: the Pacific Ocean, the Atlantic Ocean, the Indian Ocean and the Arctic Ocean. The water body which surrounds the continent of Antarctica is only an extension of the         Pacific, Atlantic and Indian Oceans.
1.    The Pacific Ocean – It separates Asia and Australia from North America. It is the largest of all the oceans. It is estimated that it covers an area of about 4, 166,884, 380 sq km which is greater than the area of all the continents put together. It is not only the          largest but also the deepest of all the oceans. Mariana Trench in the Pacific Ocean (about 11,022 metres deep) is the deepest place in the world.
2.    The Atlantic Ocean – It separates Europe and Africa from the North and South Americas. It is the busiest ocean in the world as all the important sea routes pass through the Atlantic Ocean. There are many important harbours on its coastline.
3.    The Indian Ocean – It is the only ocean named after a country, i.e. India. It lies to the south of India, west of Indonesia an Australia, and east of Africa.
4.    The Arctic Ocean – It surrounds the North Pole and lies within the Arctic Circle. A narrow stretch of water called Being Straits connects it with the Pacific Ocean. It is bound by Russia, Scandinavia, Greenland, Canada and Alaska?

Importance of Oceans
    Oceans have got a great importance of their own from many points of view :
    (1)    The presence of large quantities of water in the oceans is responsible for moderating the temperature.
    (2)    The occur currents often keep the hot countries quite cool and cold countries quite warm. In this way, they have a moderating influence on the climate of various countries.
    (3)    The tides keep the sea-shores quite clean.
    (4)    Oceans provide abundant water vapour to the atmosphere which results in rains on the plains.
    (5)    Oceans help in maritime activities and promote trade.
    (6)    Oceans provide an abundant source of food for mankind.