Sunbeam Hot Springs
Sunbeam Hot Springs runs at a scalding 169 degrees Fahrenheit directly beside the Salmon River Scenic Byway, making it one of Idaho's hottest roadside thermal features. The source water is dangerously hot, but it cools as it cascades over rocks toward the Salmon River, creating pools at varying temperatures.
At 6,160 feet in the Challis National Forest, the spring sends clouds of steam across the highway on cold mornings. The water emerges clear with an alkaline pH of 9.0 and carries little mineral load at 291 mg/L total dissolved solids. Where the thermal flow meets the cold Salmon River, visitors find the temperature gradient they need. The river canyon here is narrow and dramatic, with steep forested slopes rising from both banks. Annual snowfall reaches 125 inches, and air temperatures average just 40.2 degrees.
The source water at 169 degrees causes severe burns on contact. Only soak where thermal water mixes with river water in naturally cooled pools at the river's edge. Pole Flat Campground sits 4.6 kilometers away with vault toilets, drinking water, and sites for vehicles up to 32 feet. The Scenic Byway provides year-round road access, though winter conditions can be icy. Arrive early on summer weekends.
Sunbeam sits on the Yankee Fork mining district's thermal corridor, where water circulates deep along the Sunbeam Fault before returning at temperatures confirming extreme geothermal gradient. USGS measurements recorded 76.5 degrees Celsius at the source. The 128.8-degree differential above ambient air is among the highest in Idaho. Early miners and settlers used these springs beginning in the 1870s when the area saw intensive gold and silver extraction.
The water at Sunbeam Hot Springs is alkaline (pH 9.0) with 291 mg/L total dissolved solids.
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This campground is away from the main road and up the hill overlooking the river and the dredge ponds. Campsites include picnic tables tent pads fire rings with cooking grills. Campground amenities include a vault toilet and drinking water. Sites accommodate trailers and motorhomes up to 32 feet long.
Sunbeam Hot Springs sits at 6,160 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 25% stronger than at sea level, so bring sunscreen and drink more water than you normally would.
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Sunbeam Hot Springs is road-accessible, so you can bring more gear. The water is dangerously hot — bring water shoes and test pools carefully. Cold air temperatures make a changing robe or warm layers essential.
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