Geographic Variation in Salinity (00:00:59)[11-Feb-10] Very salty parts of the world's ocean are the Mediterranean Sea and also the Red Sea. In fact, those areas are some of the saltiest places we know in the global ocean. The reason they are so salty is that there is such strong evaporation because they're so warm there and they have high winds. So those places are very salty.
And also in the middle of our subtropical gyres. A gyre is a current system that moves around in a circle. The "subtropics" means that it is located in an area around 30 degrees (north) latitude all around the globe. That area is where we have very strong evaporation. That evaporation means that we lose fresh water from the surface. And we lose more fresh water from the surface than we actually gain through precipitation. That area is what we call "the ocean deserts".
Now on the fresh side, we have very fresh water near the coastlines and that's because we have the river waters flowing in. And we also have fresh water near the high latitudes where we have ice. Credit: Susan Lozier.