Hydrosphere Contents

4. Oceans

The oceans are the most important single reservoir in the hydrosphere

The oceans contain 97% of all water on the planet, and cover 71% of the Earth's surface reaching depths of 10,000 metres. They are the ultimate source of all the freshwater on Earth. Life originated in the seas and study of current life in our present seas can improve our understanding of the origins of life. Over aeons life in the sea has developed into a vast array of complex ecosystems including coral reefs, estuaries, and the deep sea communities around hot spring vents.

Oceans around the world.

What percentage of the planet's water do the oceans contain and what percentage of the Earth's surface do they cover?