Reed River Hot Spring
Reed River Hot Spring is inside Gates of the Arctic National Park, on National Park Service land, North Slope Borough, Alaska. Barrow is the nearest town listed, about 95 miles out. Access is open, which in a park this remote means nothing stops you except distance. The USGS sampled the water in August 1979, noting iron among the minerals, and left no temperature in the record.
Forty-three miles from the closest road, inside national park backcountry. The file names no trail and no cabin. Elevation is modest. Snow runs to something like nine feet over a season and the yearly average temperature is well below freezing. Precipitation is moderate.
A park-service backcountry trip, full stop. Check current rules with Gates of the Arctic before going. The water chemistry is from 1979, nearly fifty years back, with dissolved solids on the low side and a pH close to neutral; none of that tells you if it is warm enough to sit in. Nothing outside summer makes sense. No fee or campground is listed.
The water at Reed River Hot Spring is neutral (pH 6.9) with 498 mg/L total dissolved solids.