About 70 percent of the Earth's surface is covered with water. Think of water bodies and you might imagine lakes, streams and rivers.
But all these taken together barely hold 3 percent of the total water found on our planet. The rest of it is part of the oceans.
There are five oceans in the world - Pacific, Atlantic, Indian, Arctic and Antarctic. Pacific Ocean, which is the largest, spreads over an area which is more than the total combined area of all the continents.
During its birth, the Earth was a giant burning fire ball. When the Earth started cooling slowly, it was enveloped by clouds of gases.
Because of these clouds, it started raining heavily. But as the Earth's surface was still very hot, the raindrops falling on it would evaporate.
These would again come down to the Earth in the form of rains. This cycle continued for millions of years.
Slowly the Earth's crust became cold and tough and the rain-water boiled no more, but the heavy down-pour continued for thousands of years.
The low-lying areas of the Earth were filled with the water of these heavy rains forming huge water covered areas. These vast bodies of water on the surface of the Earth are today's oceans.
