Hot River
Hot River forms where thermal springs mix with cold stream water at 5,685 feet elevation near Mammoth Hot Springs in Yellowstone National Park. The resulting warm river reaches 136 degrees Fahrenheit in sections, flowing 96.1 degrees above ambient air temperature. Located 219.4 meters from Old North Entrance Road, the feature is accessible via a short walk through the park's northern thermal area.
The thermal river flows through the Mammoth thermal district at Yellowstone's northern boundary, where travertine terraces dominate the landscape. At 5,685 feet elevation, the area sits lower than most of Yellowstone's interior, receiving 24.4 inches of annual precipitation and 111.6 inches of snow. The Gardner River drainage system collects both cold mountain runoff and hot spring discharge, creating the warm-water environment. Open sagebrush slopes mix with Douglas fir and juniper on surrounding hillsides, while the immediate riverbanks support willows and grasses adapted to warm, mineralized water. The Gallatin Range rises to the west.
Visit May through October when roads are reliably open; winter brings severe cold to this 5,685-foot elevation despite the lower altitude. Mammoth Campground sits just 1.3 kilometers away, requiring reservations starting in April. The warm river attracts wildlife including elk and bison year-round; maintain safe distances. Do not enter the water—temperatures fluctuate unpredictably and thermal features can cause severe burns. Combine with visits to Mammoth Hot Springs terraces, Fort Yellowstone historic district, and wildlife viewing in the Gardner River valley.
The feature's name straightforwardly describes its nature: a river made hot by thermal input. The Mammoth area was well-documented during early Yellowstone exploration, with Fort Yellowstone established here in 1886 when the U.S. Army managed the park. The thermal features drew Indigenous peoples for millennia before European contact, though specific cultural associations with this particular river segment are not well-documented. The area became part of the national park in 1872 and has remained in protected status since.
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Overview Starting Tuesday April 15th, the Mammoth Campground is open and reservations are required. For reservations at the campgrounds managed by Yellowstone National Park Lodges (Fishing Bridge RV Park, Bridge Bay, Canyon, Madison, and Grant Village campgrounds), please visit the Yellowstone National Park Lodges Camping website. Recreation There are many recreational opportunities in the Mammoth Hot Springs and the North area. Visit these pages to learn more:Boating Fishing Hiking Phot...
Hot River sits at 5,685 feet above sea level, way above the mile-high mark. You may not feel the altitude strongly, but hot water still dehydrates you faster at elevation. UV is about 23% stronger than at sea level, so bring sunscreen and drink more water than you normally would.
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Hot River is road-accessible, so you can bring more gear. The water runs hot, so extra hydration is key. Cold air temperatures make a changing robe or warm layers essential.
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