In the Southern Hemisphere there is 4 times more ocean than land. Ratio between land and ocean is almost equal in the Northern Hemisphere. The water found in the ocean basins is primarily a byproduct of the lithospheric solidification of rock that occurred early in the Earth's history. A second source of water is volcanic eruptions. The dissolved constituents found in the ocean come from the transport of terrestrial salts in weathered sediments by leaching and stream runoff.
Sea water is a mixture of water and various salts.
The presence of salt in sea water allows ice to float on top of it. These gases enter the ocean from the atmosphere and from a variety of organic processes. Sea water changes its density with variations in temperature, salinity, and ocean depth. Sea water is least dense when it frozen at the ocean surface and contains no salts. Highest sea water densities occur at the ocean floor.