Salinity
Now you know why seawater is so salty. Seawater, contains many dissolved substances, including salts. Rather than being uniform throughout, seawater's salinity varies from place to place due to changes in the amount of pure water present. Precipitation, runoff and melting icebergs contribute to these changes in salinity. Salt escapes seawater through the spray caused when waves crash against the shore, as well as into salt deposits within marine sediment.
Extend Your Learning
In 2010, NASA and a Mississippi High School conducted an important examination of coastal salinity; specifically, they investigated the intrusion of saltwater into coastal freshwater areas. Read the press release, NASA Partners with Mississippi School on Coastal Salinity Project.