Over 70 percent of the earth's surface is covered by water. In fact, when seen from space, our earth looks blue, because of the large bodies of water which cover most of it. Although we speak of separate oceans, the world is really covered by one huge ocean in which the continents are islands!
There are four main oceans: the PACIFIC, ATLANTIC, INDIAN, and ARCTIC.
The average temperature of all oceans is about 39 degrees F . But the oceans in different parts of the world can have very different climates! Tropical oceans, which are near the equator, are warm and clear on the surface. The equator is an imaginary belt which circles the earth and divides it into two halves. The areas of land and water which are near this belt are called the tropics, and are always warm. But in the cold polar regions of the far north and far south, the ocean is so cold that its' surface is frozen! Huge blocks of ice called Icebergs drift in these seas.
The sun's heat warms only the surface of the water. Deep down, oceans everywhere are cold, dark, and still.
It is the only biome with no insects.