Lake Vanda is a three-mile-long lake in the Wright Valley with no outlet. Its level rises and falls with inflow from the Onyx River, which is fed by seasonal glacial melt. The surface ice insulates in winter and allows extensive heat transfer during the summer. The result is a water temperature near the lake bottom that averages around 25 degrees Celsius above zero. The lake also has a high saline content because salts fall to the bottom when the surface water evaporates, which means the surface is fresh while the layers near the bottom are more salty than the Dead Sea.