Yellowstone Lake

Yellowstone Lake Because of its size and depth and the area's prevailing winds, Yellowstone Lake can sometimes be whipped into a wild inland ocean. During late summer, Yellowstone Lake becomes thermally layered with each of several water layers having a different temperature. The topmost layer rarely exceeds 66°F, and the lower layers are much colder. Because of the extremely cold water, swimming is not recommended. Survival time is estimated to be only 20 to 30 minutes in water of this temperature.