Yellowstone Lake sits at 7,733 feet, and its average water temperature is just 41°F. It freezes over in late December or early January and usually thaws in late May or early June, so plan this as a lakeside stop rather than a swim. The lake supports North America’s largest wild cutthroat trout population, while introduced lake trout threaten the native fish. Its name has changed over time: an 1826 fur-trapping party that included Daniel Potts, Bill Sublette, and Jedediah Smith called it Sublette Lake; by 1831, Warren Ferris was using Yellow Stone Lake.