Ocean – A very deep and large sea which has saline water is called an ocean. The oceans cover at around 71 percent of the earth’s surface. In fact, the oceans constitute about 97 percent of the world’s water resources. The remaining 3 percent of the world’s water is in the form of ice in the polar regions of the earth. The average depth of the oceans is about 3.9 kilometers. All the oceans are interconnected by water and characterized by saline water (salty water).

There are five oceans on the earth

1. Pacific Ocean
2. Atlantic Ocean
3. Indian Ocean
4. Arctic Ocean
5. Antarctic Ocean

The Pacific Ocean is the biggest and deepest ocean of all. Actually, the Pacific Ocean is so big that it can accommodate all the seven continents of the earth. The maximum depth of Pacific ocean is about 4.2 kilometers.

Functions of Oceans

The important functions performed by the ocean are as given below

1. The oceans regulate the temperature of land
2. The oceans act as a dust-bin for throwing unwanted waste material of the land.
3. The oceans act as reservoir of resources like fossil fuels, sea-foods, metals and salts.
4. The oceans act as a medium of transport by boats and ships.
5. The oceans acted as a cradle for the origin (birth) of primitive life.
6. The oceans dissolve out excess carbon dioxide from the atmosphere and hence prevent the excessive heating of earth by decreasing the green-house effect.