Why is Sea Water Salty ?

Sea water contains many minerals . They have all been washed out of the land and carried to the sea by rivers or glaciers. When sea water evaporates , these minerals remain in the sea and become more concentrated . This makes the water salty. The saltiest sea of all is the dead Sea.

Salt (sodium chloride ) makes up about 85 percent of all the minerals in sea water. The saltiness of deep sea water is fairly constant , but near the surface it varies from place to place . It is low where lots of fresh water is added from rivers.