Oceans

Water covers three fourths of the Earth's surface. 97% of this water is in the ocean, it exists as salt water.

Another 2% of our water is locked in polar icecaps and glaciers which are in the oceans of the world. In most substances solids are more dense than liquids. But, the properties of water make it less dense as a solid. That's why ice floats on water. This plays an important role in our oceans ecosystems. The floating ice insulates and protects animals and plants living in the water below them.