Why is the Dead Sea so salty?

The Dead Sea, on the border of Jordan, Israel and the West Bank, sits at the lowest point on land, about 430 metres below sea level. The Jordan River and smaller streams carry dissolved minerals into it, but there is no river flowing out. In the hot desert climate, water evaporates quickly, leaving the salts behind. Over millions of years this has raised the salinity to about 34 percent, compared with about 3.5 percent for the open ocean. The extreme saltiness makes the water so dense that swimmers float effortlessly, and almost no multicellular organisms can survive in it, hence its name.