When you mix hot water and cold water, what do you end up with? The potential for an awesome swimming hole. The Boiling River in Yellowstone National Park is just such a place. The Boiling River meets the much colder waters of the Gardner River and gives you a fantastic place to soak. It’s one of the few easily accessible places to swim in natural hot water in Yellowstone – you only have to walk 10 minutes to get there.
The Boiling River is believed to be runoff from Mammoth Hot Springs. The waters of the Boiling River break out from underground just above the swimming area, then flow into the much larger Gardner River. It’s a very unique experience – you can be standing with one foot in water that is too warm for comfort and the other foot in ice-cold river water. Even as you lie in the river, you could feel the currents change and your chosen spot might become too warm – or cold.
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The Boiling River is more of a soaking hole than a swimming hole. The Gardner River flows too quickly to venture too far away from the shore. A long rock wall separates the swimming area from the rest of the river.
To get to the Boiling River, drive north from Mammoth Hot Springs or south from Gardiner, Montana. At the boundary between Montana and Wyoming – and just south of the 45th Parallel – you will see parking areas on both sides of the highway. The parking areas are about a mile north of the Mammoth Hot Springs campground. The Park Service doesn’t go out of its way to publicize the Boiling River and there aren’t any signs from the main highway. However, the area is easy to find if you watch for the Montana-Wyoming boundary.
If space is available, you’ll want to park in the eastern lot; the trail to Boiling River starts at the south end of the parking area; a large sign marks the trailhead. There are no changing facilities at the Boiling River, so change into your swimsuit in your car or in the outhouse at the parking area.
The walk from the parking lot is an easy 10 minute jaunt south down Gardner Canyon. You’ll follow an easy, level trail down the western shore of the Gardner River. After about a half mile, the Boiling River emerges and you’ll see the swimming area.
This area can be very popular, so don’t be surprised to be sharing the waters with dozens of other people. If you’re lucky enough to get to the Boiling River on a quieter day, you’ll enjoy the solitude of lying in the river, surrounded by the Gardner Canyon and with a view of southern Montana mountains to the north. With the hot waters meeting the cool waters, it can take a little work to find the ideal soaking spot, but once you’ve located one, the soothing warm waters are outstanding. If you’re hiking in the Mammoth Hot Springs area, the Boiling River is a great way to wrap up your day, and if you’re staying in Mammoth or Gardiner, this is a fantastic side trip.
Naturally, several rules apply to the area. You’re not allowed in the water after dark and alcoholic beverages are not allowed. You’re only allowed in the water where the Boiling River meets the Gardner River – stay out of the Boiling River itself. Additionally, the area will probably be closed in high water seasons – it didn’t open until mid-July this year.