Lake Assal, Djibouti: 502 feet below sea level

Lake Assal, meaning "honey lake," is a crater lake in central-western Djibouti that lies 509 feet below sea level, making it the lowest point on land in Africa. No water flows out from it, and the water that's already there evaporates fairly fast, making it 10 times saltier than the sea.

No one is sure how this lake came to be, but some believe that the area was flooded by a nearby bay, while others think it came about after sea levels began to rise and flow into the crater. Some explorers thought that volcanic convulsions may have severed the link between Lake Assal and the Gulf of Tadjoura.