Number of grams of salt in one kilogram of water is the best description of the salinity of ocean water.
Salinity is a measure of dissolved salts in water bodies such as oceans, rivers, seas etc. Salinity is calculated as the amount of salt (in grams) dissolved in one kilogram (1,000 grams) of seawater. Sodium chloride are the main salts with other elements such as magnesium, calcium and potassium that can be found in sea water.