The surface of our planet Earth is more than two thirds (72 percent) covered by water. We call small stretches of water seas and larger expanses oceans, but they are all part of one gigantic World Ocean that is moving and changingand affecting our livesall the time. Without seas and oceans, we would not survive. But where did all this water come from? What does it do? Why do we need it?
Fiona Macdonald studied history at Cambridge University and at the University of East Anglia. She has taught in schools, adult education and university, and is the author of numerous books for children on historical topics.