Earth Observatory NASA web page share with the public the images, stories, and discoveries about climate and the environment. This is the winter selection. The world’s saltiest body of water – Don Juan Pond in the lowest part of Upper Wright Valley in Antarctida is so salty that its calcium-chloride rich waters rarely freeze. With a salinity level over 40 percent, Don Juan is significantly saltier than most of the other hypersaline lakes around the world. The Dead Sea has a salinity of 34 percent; the Great Salt Lake varies between 5 and 27 percent. Earth’s oceans have an average salinity of 3.5 percent.