Perhaps the most important substance dissolved in the
ocean is salt.
Everyone knows that ocean water tastes salty.
That salt comes from mineral deposits that find their way
to the ocean through the water cycle.
Salts comprise about 3.5% of the mass of ocean water.
Depending on specific location, the salt content or salinity
can vary. Where ocean water mixes with fresh water, like at the
mouth of a river, the salinity will be lower.
But where there is lots of evaporation and little
circulation of water, salinity can be much higher.
The Dead Sea, for example, has 30% salinity—nearly
nine times the average salinity of ocean water.
It is called the Dead Sea because so few organisms can
live in its super salty water.