Large, continuous body of salt water. Ocean covers nearly 71% of the Earth's surface and is divided into major oceans and smaller seas. The three principal oceans, the Pacific, Atlantic, and Indian, are largely delimited by land and submarine topographic boundaries. All are connected to what is sometimes called the Southern Ocean, the waters encircling Antarctica. Important marginal seas, primarily in the Northern Hemisphere, are partially enclosed by landmasses or island arcs. The largest are the Arctic Ocean and adjacent seas, Caribbean and adjacent waters, Mediterranean, Bering Sea, Sea of Okhotsk, Yellow and China Seas, and Sea of Japan.