Shoshone Lake

Shoshone Lake is a U.S. backcountry lake with the area of 8,050 acres elevated at 7,795 feet in the southwest section of Yellowstone National Park, Wyoming. It lies at the headwaters of the Lewis River a tributary of the Snake River. The U.S. Fish and Wildlife Service believes that Shoshone Lake is the largest backcountry lake in the lower 48 states that cannot be reached by a road. The Yellowstone Caldera is located within the lake.

Source: Wikipedia