The oceans contain 99 percent of the living space on Earth, covering over 71 percent of its surface. In all, the oceans contain 328 million cubic miles/1.34 billion cu. km of water.
Ninety-seven percent of the water on Earth is seawater. Less than 1 percent is fresh, while another 2 to 3 percent is contained in glaciers and icecaps. The surface area of the Pacific Ocean alone exceeds the surface area of all landmasses combined.
While land-based volcanic eruptions garner most of the publicity, more than 90 percent of all volcanic activity occurs in the oceans. Scientists have, in fact, located the largest known concentration of volcanoes along the sea floor of the South Pacific in an area roughly the size of New York state. The area contains over 1,100 volcanic cones and seamounts, two or three of which could erupt at any time.