Kirkham Hot Springs

Hot spring water cascades down a rocky hillside along the South Fork Payette River, collecting into a series of primitive pools at the river's edge before the cooler river water tempers things down. The geology behind it is straightforward: Kirkham is part of the South Fork Payette Geothermal System, a chain of thermal springs running along faults that fracture the Idaho batholith, kept active by seismic activity in the region. The pools are unimproved — rocky and gravelly underfoot — and the site sits open to the sky with little shade, so expect full sun in summer.

The Boise National Forest manages this as a day-use-only site with a gate that closes at 9 p.m. A per-vehicle day-use fee applies whether you park inside the gate or along Highway 21; an interagency pass covers it. Vault toilets and changing rooms are on site, but there is no potable water. The hot spring runoff channels above the pools can be scalding, so watch your footing on wet rock — the terrain is natural, with no constructed surfaces. The site draws crowds on summer weekends, so an early arrival makes a real difference.

Highway 21 through this stretch is also designated the Ponderosa Pine Scenic Byway, and the Banks-Lowman Road running west is the Wildlife Canyon Scenic Byway — both corridors carry riders through canyon terrain with river views and a handful of other hot springs access points along the way. Kirkham slots naturally into a ride that connects Boise to the Sawtooth region, requiring only a short walk from the road.