Smith Cabin Hot Spring
Smith Cabin Hot Spring sits just 65 feet from Middle Fork Road in the Boise National Forest, delivering 138-degree water at 3,560 feet elevation — one of the hottest roadside springs along the Middle Fork Boise River corridor. USGS data confirms 140-degree water with a pH of 9.5 and remarkably low mineral content.
The spring emerges beside the gravel road where the Middle Fork Boise River carves through a narrow, forested canyon in Boise County. Ponderosa pine shade the banks, and the river runs within earshot. The water chemistry is among the purest of any hot spring in the area — just 44 mg/L sodium, 18 mg/L sulfate, and 2 mg/L chloride. Steam drifts across the road surface in cool weather, marking the spring's location before you see it.
Smith Cabin Hot Spring takes its name from a former forest service or settler cabin that once stood nearby. The spring taps the same deep geothermal corridor that feeds Sheep Creek Bridge and other thermal features along the Middle Fork. Its extreme alkalinity and near-zero calcium and magnesium content indicate water that has spent considerable time circulating through the granitic Idaho Batholith before surfacing.
The spring is immediately roadside — no hiking required. However, the source temperature of 138 degrees is dangerously hot. Look for spots where it meets the river or cooler side streams. Middle Fork Road can be rough and narrow; check seasonal conditions before driving. Ninemeyer Campground is 5.6 km away but has limited amenities due to wildfire damage. Best access is mid-May through late September.
Is Smith Cabin Hot Spring worth visiting?
Best for
- Hot spring soaking
- Easy day trips
- Overnight camping trips
The water at Smith Cabin Hot Spring is alkaline (pH 9.5).
Some links are affiliate links. We may earn a commission at no extra cost to you.
Overview:Due to a wildfire, there are no amenities at the campground. Currently there are no developed campfire rings therefore when Stage 1 fire restrictions area in effect, no fires are permitted.A stay at Ninemeyer Campground enables guests to enjoy all the beauty and recreation offered along the (Middle Fork Boise River Road) Forest Service (FS) Road 268. Weather is usually good from mid-May through late September and is easily accessible by car in good weather, although the road is some...