Sea

A sea is a great expanse of saline water associated with an ocean, or a large, generally saline, lake that lacks a natural opening such as the Caspian Sea and the Dead Sea. The term is used colloquially as identical with ocean, as in "the tropical sea" or "down to the sea shore", or even "sea water" to refer to water of the ocean. Large lakes, such as the Great Lakes, are at times referred to as inland seas. Many seas are marginal seas, in which currents are caused by ocean winds; others are Mediterranean seas, in which currents are caused by differences in salinity and temperature.