Elkhorn Hot Spring
Elkhorn Hot Spring, better known locally as Boat Box Hot Spring, delivers 136-degree water into a metal soaking tub built into the bank of the Salmon River, about 3 miles from Stanley along the Salmon River Scenic Byway. The name references an earlier wooden tub that annual spring floods repeatedly destroyed before the current setup replaced it.
The tub sits at river level with the Salmon flowing just feet away, its cold current available for contrast soaking. Sawtooth peaks line the skyline to the west, their granite faces catching afternoon light. Ponderosa pine and cottonwood shade the bank above. At 6,155 feet, the air is thin and cool even in summer. Snow averages over 12 feet per year, and the river corridor funnels wind through the canyon. A plastic tube channels the 136-degree source water down to the tub, where soakers regulate temperature by adjusting the flow.
The spring sits on Idaho Department of Lands property along a stretch of the Salmon River where deep faulting allows superheated groundwater to surface. This section of the river corridor contains multiple thermal features, evidence of the extensive geothermal system underlying the Sawtooth Valley. The area's geology reflects the Idaho Batholith's fractured granite, which provides pathways for deep water circulation. Stanley has served as a gateway to these springs since ranching families settled the valley in the late 1800s.
Sunny Gulch Campground, 5 miles away along the Salmon River, offers reservable sites with river access and trout fishing. The spring is a short walk from the Scenic Byway. Water arrives at 136 degrees F, so use the flow control to mix to a comfortable temperature. The tub fits two to three people. Spring flooding can damage or displace the tub, so check recent reports before visiting. Winter access requires cold-weather gear.
Is Elkhorn Hot Spring worth visiting?
Best for
- Hot spring soaking
- Easy day trips
- Overnight camping trips
- Winter soaking with dramatic temperature contrast
Overview Sunny Gulch Campground sits along the shores of Salmon River in the forests of central Idaho. Recreation Excellent fishing is right out your back door on the Salmon River, with rainbow trout, Westslope cutthroat trout and occasional hybrid cutbows and bull trout available. Sunny Gulch lies in the heart of the Sawtooth National Recreation Area. A myriad of excellent hiking and biking opportunities are available, and an estimated 750 miles of trails crisscross the valley and surround...