Page "Atlantic Ocean" Paragraph 27

On average, the Atlantic is the saltiest major ocean ; surface water salinity in the open ocean ranges from 33 to 37 parts per thousand ( 3. 3 – 3. 7 %) by mass and varies with latitude and season.

Evaporation, precipitation, river inflow and sea ice melting influence surface salinity values.

Although the lowest salinity values are just north of the equator ( because of heavy tropical rainfall ), in general the lowest values are in the high latitudes and along coasts where large rivers enter.

Maximum salinity values occur at about 25 ° north and south, in subtropical regions with low rainfall and high evaporation.