Water is everywhere. It covers almost 70 percent of Earth's surface. It forms the oceans and flows as rushing rivers. The atmosphere not to mention clouds is a vast storehouse of water in the form of the gas called water vapor. Billions of tons of water are locked up as the enormous ice caps that sit on the top and bottom of the world. If all of that icy water were to melt, it would cause a rise in sea level of about 260 feet (80 meters). Coastal cities the world over would be flooded beyond repair.