Is the proportion of dissolved salts to pure water.

The proportion of dissolved salts to pure water in the ocean is known as salinity. This is commonly measured in parts per thousand. For example, if the salinity of an ocean is 35 parts per thousand, or ppt, this means that in every kilogram, or 1000 grams, of ocean water, there are 35 grams of salt present. The higher the quantity of parts per thousand, the saltier the water, which also means the higher the salinity.