This near-vertical photograph shows Lac Assal (Lake Assal) in Djibouti, the third lowest surface in the world (excluding the ocean basins) and the lowest point in Africa at 155 m (510 ft) below sea level. Lake Assal sits in a rift valley, a depression where the earth's crust has split and adjacent areas have moved with respect to one another. The lake is located in the Danakil Desert near the western end of the Gulf of Aden. Because Lac Assal has no outlet, it is ten times saltier than the ocean and is the most saline body of water in the world. The evaporation rate of Lake Assal is very high because summer temperatures sometimes reach 52°C (125°F), and are accompanied by strong dry winds. The surrounding plain (visible on the image to the right of the lake), once the lake floor, is a glistening expanse of salt. The region surrounding the lake is mostly a stony desert with isolated plateaus and highlands. Lava flows from an ancient volcano are visible just to the left near the shore of the lake. Image courtesy of NASA.