Why is the ocean salty?

Ocean salt primarily comes from rocks on land

mussels growing in brine pool

Some areas of the ocean are saltier than others. This image shows methane mussels living at the edge of a underwater brine pool in a cavern at a depth of 650 feet in the Gulf of Mexico. The pool of brine in the foreground is nearly four times as salty as seawater and is so dense that a submarine can float on the pool (in fact, this photo was shot from a submarine).

Salt in the ocean comes from rocks on land.


As the rain erodes the rock, acids in the rainwater break down the rock. This process creates ions, or electrically charged atomic particles. These ions are carried away in runoff to streams and rivers and, ultimately, to the ocean. Many of the dissolved ions are used by organisms in the ocean and are removed from the water. Others are not used up and are left for long periods of time where their concentrations increase over time.

Two of the most prevalant ions in seawater are chloride and sodium. Together, they make up over 90 percent of all dissolved ions in the ocean. Sodium and Chloride are 'salty.'


By some estimates, if the salt in the ocean could be removed and spread evenly over the Earth’s land surface it would form a layer more than 500 feet thick, about the height of a 40-story office building.

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