While Boiling River Trail is about as easy and straightforward as they come, the destination is completely unconventionally. The 1.25-mile round trip hike ends at one of America’s strangest swimming holes where a stream of water cooked by Yellowstone’s hydrothermal features mixes with cold river water. Wear your bathing suit and take a dip in this remarkable hot springs!
Boiling River Trail is located in the Mammoth Hot Springs area near the north entrance of Yellowstone National Park. An underground discharge of water from a mysterious source beneath nearby hydrothermal terraces flows out of the ground at over 100 degrees. The channel joins the otherwise cold waters of the Gardner River, creating a blended pool that is too good to pass up.
The trail starts just north of the Montana border at the 45th parallel (halfway between the North Pole and the equator) and heads south, quickly entering the state of Wyoming. The dirt trail follows the west bank of the northbound Gardner River, a choppy flow that does not look too swimmer-friendly at the start. Boiling River Trail is hard packed, level, and wide, so this hike that can be done in swim trunks and flip-flops.
Looking down the scream of scalding hot water
After half a mile, the trail circles a seductive looking stream emerging from an outcropping on the riverbank. The clear water may look appealing, but don’t dip your toes in yet. You can get immediate and severe burns by entering the runoff channel directly. It simmers at extreme temperatures between 113 to 140 degrees. Instead, follow the trail to the end where the stream pours into the significantly colder waters of the Gardner River. A sheltering line of rocks creates a protected area on the river suitable for bathers. The river is deep enough for you to sit comfortably in the enclosed flow, but can you find the right balance between hot and cold?
As you pursue the perfect mixing point between the two waters, one side of your body can feel like it’s burning, while the other side can feel like it’s freezing. The temperature differences are drastic. No, you can’t just adjust the hot and cold knobs by the faucet, but it is amazing how much you can alter the temperature by shifting a couple inches toward or away from the stream. It is a fun exercise at one of the world’s most bizarre confluences. Once you find that perfect spot, Boiling River is a great place to relax. You aren’t likely to find anywhere else like it.
As a precaution it is recommended that you do not put your head below the surface. A sign at the trailhead warns:
Many of Yellowstone National Park’s thermally-influenced waters contain organisms that are known to cause serious skin rashes, infections, and/or primary amoebic meningitis, which can be quickly fatal. The thermal waters of Boiling River have been shown to support the organisms that can cause Primary amoebic meningoenchephalitis and Legionnaire’s disease. Avoid submerging your head and inhalation of thermal steam. If you have any signs of symptoms of irritation or disease seek medical help immediately. Swim at your own risk.
Hundreds of people swim in Boiling River each day. While the dangers are minimal, precautions should be taken.
With just 50 feet of elevation gain along the way, this trail is suitable for almost everyone. Boiling River is open for swimming daily between 9 a.m. and 5 p.m. No bikes or pets are allowed on the trail. Soap (including biodegradable), food, and beverages are not allowed in the hot springs. No nudity. Boiling River is often closed to the public during the spring when the Gardner River flows at dangerous levels. If you are attempting this hike before mid-summer, check on the trail status with a ranger at Mammoth Hot Springs. There is an entrance fee for Yellowstone National Park, but no permit is required to hike Boiling River Trail, so get out and enjoy.
To get to the trailhead: From the Roosevelt Arch at Yellowstone’s north entrance near the city of Gardiner, Montana, drive 3 miles south on Route 89. Just before the entering Wyoming sign and just after crossing the river, turn left into a pullout for Boiling River.
From the south, drive two miles past Mammoth Hot Springs on Route 89. Just after entering Montana, and before crossing the river, turn right into the dirt pullout for Boiling River. There is a bathroom at the trailhead and overflow parking on the other side of the road.
Trailhead address: North Entrance Road (Route 89), Yellowstone National Park, Gardiner, MT 59030
Trailhead coordinates: 44.992301, -110.691211 (44° 59′ 32.28″N 110° 41′ 28.35″W)
Use the map below to create your own directions:
|Mammoth Hot Springs|
This series of boardwalks explores a park highlight, a collection of colorful hot springs terraces.
This easy 0.8-mile round trip hike climbs 100 feet to a ghostly 100-foot cascade.
This 1-mile hike starts with a head-on view of a 132-foot waterfall. Unfortunately, the final leg of the trail to the base of Tower Fall is closed due to damage from rock and mud slides.
This 1.1-mile hike circles a hillside hydrothermal area, passing bursting mudpots, bubbling hot springs, and mesmerizing milky blue pools.
|Monument Geyser Basin|
This 2.8-mile hike reaches a rarely visited hydrothermal area that is boardwalk-free and fun to explore.
|More trails in Yellowstone|
Explore other hikes to waterfalls and hydrothermal hot spots in Yellowstone National Park.
|Yellowstone National Park Campgrounds|
There are 12 developed campgrounds with over 2,000 total sites spread throughout Yellowstone.