Sea water refers to the saltwater found in oceans, seas and other large bodies of saltwater around the world. It is a mixture of various salts dissolved in water, primarily composed of sodium chloride (table salt) which gives it its characteristic taste and properties. The concentration of salt in sea water varies depending on location but typically averages about 3.5% by weight. This high salt content makes sea water denser than freshwater, allowing marine organisms to maintain buoyancy while providing a rich source of nutrients for other forms of life.