The ocean covers 321,003,271 cubic miles, or 70 percent of the Earth's surface, according to the National Oceanic and Atmosphere Administration. A cubic mile is the volume of a cube that measures 1 mile on each side. The ocean makes up 96 percent of the Earth's water.
Though there is only one global ocean, oceanographers divide it into five geographical regions: the Atlantic, Pacific, Indian, Arctic and Southern Oceans. The Pacific, Atlantic and Indian Oceans are the Earth's three major oceans. Covering more than 30 percent of the Earth's surface, the Pacific Ocean is the world's largest ocean, and the Atlantic Ocean, covering about 20 percent of the Earth's surface, is the second-largest ocean. The Southern Ocean, which is the world's smallest ocean, is located around the South Pole in the Antarctic Circle.