Sulphur Creek Hot Spring
Sulphur Creek Hot Spring in Custer County requires a genuine hike of over 1.3 miles through the Challis National Forest to reach, rewarding the effort with a remote thermal feature at 5,807 feet. Not to be confused with its Valley County namesake, this spring offers deeper solitude.
The trail crosses open slopes and forested draws in terrain that receives 142 inches of snow annually and stays cold, averaging 41.5 degrees Fahrenheit year-round. The spring emerges in a drainage where sulfur-tinged steam marks the location from a distance. The surrounding Challis National Forest is sparse at this elevation, mixing lodgepole pine with sagebrush meadows. Silence dominates here, broken occasionally by elk or the distant sound of water moving through rock.
This spring surfaces along the same network of deep faults that feeds numerous thermal features across Custer County's volcanic terrain. The Challis Volcanics, a thick sequence of Eocene-age eruption deposits, provide both the fractured pathways and residual heat that drive geothermal circulation in this region. Federal protection under the Forest Service has kept the area undeveloped and the spring in its natural state.
The 2,122-meter approach has no formal trailhead or maintained path for its full length. Carry a GPS unit and topographic maps. Snow blocks access from roughly October through June depending on the year. The nearest reservable campground is Boundary Creek, 18.5 kilometers away, which fills quickly during rafting season. Pack all water and supplies for the day hike.
Is Sulphur Creek Hot Spring worth visiting?
Best for
- Overnight camping trips
Overview Boundary Creek Campground is located at the edge of the Frank Church River of No Return Wilderness, adjacent to the boat launch for the Middle Fork of the Salmon River in Idaho. The site generally provides overnight camping for boaters waiting to launch the next day on their permit to float the Middle Fork. Of the 15 campsites, 5 can be reserved during the high-use season (June 15-Aug. 15); the remaining 10 are first-come, first-served. Outside of those dates, all 15 sites are first-...