Evaporation of ocean water and formation of sea ice both increase the salinity of the ocean. However these "salinity raising" factors are continually counterbalanced by processes that decrease salinity such as the continuous input of fresh water from rivers, precipitation of rain and snow, and melting of ice.

Do different oceans have different salinity?

Variation in salinity

The salinity of the ocean varies from place to place, especially at the surface. Much of the ocean has salinity between 34 ppt and 36 ppt, but there are places that tend to be higher or lower.

Why is the sea saltier than the ocean?

Salt in the sea, or ocean salinity, is mainly caused by rain washing mineral ions from the land into water. Carbon dioxide in the air dissolves into rainwater, making it slightly acidic. ... Underwater volcanoes and hydrothermal vents on the seabed can also release salts into the ocean.