Yellowstone Lake is the largest body of water in Yellowstone National Park. The lake is 7,732 feet above sea level and covers 136 square miles with 110 miles of shoreline. While the average depth of the lake is 139 feet its deepest spot is 387 feet. After Lake Titicaca in South America, Yellowstone Lake is the largest high altitude freshwater lake in the world.
In winter, ice nearly 3 feet thick covers much of the lake, except where shallow water covers hot springs. The lake freezes over by early December and can remain frozen until late May or early June.
