Oceans Wallpaper, #12640

An ocean (from Greek Ωκεανός, Okeanos (Oceanus)) is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface (an area of some 361 million square kilometers) is covered by ocean, a continuous body of water that is customarily divided into several principal Oceans and smaller seas. More than half of this area is over 3,000 meters (9,800 ft) deep. Average oceanic salinity is around 35 parts per thousand (ppt) (3.5%), and nearly all seawater has a salinity in the range of 30 to 38 ppt.The total mass of the hydrosphere is about 1.4 × 1021 kilograms, which is about 0.023% of the Earth's total mass. Less than 2% is freshwater; the rest is saltwater, mostly in the ocean.Much of the bottom of the world's Oceans are unexplored and unmapped. A global image of many underwater features larger than 10 kilometers (6 mi) was created in 1995 based on gravitational distortions of the nearby sea surface.Astronomers believe that Venus had liquid water and perhaps Oceans in its very early history. If they existed, all trace of them seems to have vanished in later resurfacing.