The park's largest lake is Yellowstone Lake. Yellowstone Lake covers 136 square miles and is 20 miles long by 14 miles wide. It has 110 miles of shoreline. The lake is at least 320 feet deep in the West Thumb area and has an average depth of 140 feet. Situated at an elevation of 7,733 feet, the lake remains cold the year-round, with an average temperature of 41 F.
Yellowstone Lake is the largest natural freshwater lake in the United States that is above 7,000 feet and is one of the largest such lakes in the world. Because of its size and depth and the area's prevailing winds, the lake can sometimes be whipped into a tempestuous inland ocean. During late summer, Yellowstone Lake becomes thermally stratified 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.
The lake has the largest population of wild cutthroat trout in North America. Just how these Pacific Ocean cutthroat got trapped in a lake that drains to the Atlantic Ocean puzzled experts for years. There is now a theory that Yellowstone Lake once drained to the Pacific Ocean (via Outlet Canyon to Snake River) and that fish could pass across the Continental Divide at Two Ocean Pass. Lake trout, an illegally introduced, exotic species, is now found in Yellowstone Lake and threatens the existence of the native cutthroat trout.
Fishing Cone is a hot spring located in the West Thumb Geyser Basin.
Fishing at the cone can be dangerous. A known geyser, Fishing Cone erupted frequently to the height of 40 feet in 1919 and to lesser heights in 1939.
Big Thumb Creek and Little Thumb Creek along with several other intermittent streams serve as cutthroat trout spawning streams, thus as major feeding areas for both grizzly and black bears during spawning season.
Lying in the Snake River watershed west of Lewis Lake and south of Yellowstone Lake, Heart Lake was named sometime before 1871 for Hart Hunney, an early hunter. The name does not refer to the heart-like shape of the lake.
Craig Pass, at 8,262 feet on the Continental Divide, is about eight miles east of Old Faithful on the Grand Loop Road.
Factory Hill is a 9,607-foot-high peak in the Red Mountains.
This river drains Shoshone and Lewis lakes and is a tributary of the Snake River. In 1872, members of the second Hayden survey called the river Lake Fork because it was a fork of the Snake that began in those two lakes. An 1876 map showed the river marked Lewis Fork (of the Snake), named from Lewis Lake.
This small range of mountains, located just west of Heart Lake, is completely contained within the boundaries of Yellowstone National Park.
This small lake is located about three miles south of the West Thumb bay of Yellowstone Lake.
Shoshone Lake, the park's second largest lake, is located at the head of the Lewis River southwest of West Thumb. le.
Shoshone Lake is 205 feet at its maximum depth, has an area of 8,050 acres, and contains lake trout, brown trout, and Utah chubs. Originally, Shoshone Lake was barren of fish owing to waterfalls on the Lewis River. This large lake is the source of the Lewis River, which flows to the Pacific Ocean via the Snake River system.
This point on the Grand Loop Road is located halfway between West Thumb and Old Faithful.
The Snake River is a major tributary of the Columbia River and has its headwaters just inside Yellowstone on the Two Ocean Plateau.