Have you ever swallowed a gulp of seawater? If so, you know that it is not fit to drink. It tastes very salty. You know that rivers on land empty into the ocean. River water is not salty. So why is the ocean salty?
 
Sodium chloride is the most common salt dissolved in ocean water. You know this compound as table salt. How does it get into the ocean?
 
Most of the salt in seawater does come from the rivers that empty into it. As the fresh water flows over the land, the soil is eroded. Minerals are dissolved in the water. These minerals include sodium and potassium. They are carried to the ocean.
 
Waves are another cause of salts in ocean water. As waves constantly flow over the shore, they dissolve the minerals in the rocks. The minerals are added to the water.
 
Volcanoes under the sea also add chemicals to the water. When volcanoes erupt, gases are released. One of these gases is chlorine. Chlorine bonds with the sodium in the water, and forms salt.