Entry No. 33 — the Boise file — filed under: soak
Kirkham Hot Springs
A short staircase off Highway 21 drops down to a cluster of rock-walled soaking pools perched right on the edge of the South Fork Payette River. Steaming hot water actually pours over the cliff as small waterfalls, so you can sit under a hot cascade with the cold river rushing past below. Pools range from comfortably warm to around 110 degrees, the hottest sitting closest to the cliffside source where the spring water spills over the rocks.
The story
You didn't hear it from us, but Idaho's granite foundation is held together by geothermal pressure waiting for an exit. Five miles east of Lowman on Highway 21, deep subterranean groundwater gets superheated against the fractured Idaho batholith and shoots upward through fault lines along the South Fork Payette River. Instead of bubbling out as quiet, muddy seeps, the water bursts through cliffside vents and tumbles over granite ledges as natural hot waterfalls, cascading into hand-stacked rock pools inches above the roaring river.
Because a short staircase right off the Ponderosa Pine Scenic Byway makes it ridiculously accessible, Kirkham has endured a long, tense relationship with its own popularity. Years of midnight ragers, litter, and trampled riverbanks forced the U.S. Forest Service to intervene, stripping away overnight camping at the immediate soaking site, locking the gates at 9:00 p.m., and enforcing strict day-use fees. The thermal waterfalls still spill warm over the rocks, but the era of wild, lawless soaking here is officially over.
What it's like
You'll park in the paved lot off Highway 21, drop five dollars into the fee box or display an interagency pass, cross the footbridge, and walk down the concrete stairs into a blanket of sulfurous steam. The vibe depends entirely on your timing: pull up at noon on a summer Saturday and you'll be squeezed shoulder-to-shoulder with highway road-trippers and loud crowds in every pool. The move is arriving right at 7:00 a.m. on a chilly weekday. Wear grip-bottom water shoes—the wet granite is coated in slick algae—and climb into the upper pools sitting around 110 degrees right beneath the cliff face, letting a hot waterfall hit your back while the icy Payette surges past below.
The move: Arrive early on a weekday morning to beat the crowd and soak under the hot waterfall with the Payette roaring beside you.
📍 Before you go Day use only, 7am-9pm, no overnight camping; $5 parking fee or interagency pass; lot fills by mid-morning on summer weekends; rocks are slippery, wear water shoes.
- 📍 Lowman
- 💸 Free
- ⚡ Up for anything
- 🌗 Outdoors
Where: Highway 21, Lowman, ID 83637
Hours: Added 2026-06-24 — confirm current hours before you go.
Pair it with
- Idaho City Historic District & Boot Hill Cemetery — Positioned 20 miles south along Highway 21, this 1862 gold rush burial ground offers a gloomy historical leg-stretcher on the drive between Boise and Lowman.
- Idaho City & Boise Basin Museum — Break up your drive back down Highway 21 by stopping in Idaho City to inspect 1860s mining tools housed inside a former post office.
- Old Idaho Penitentiary — Pair your wild mountain river soak with a return trip to Boise's East End to tour the harsh sandstone cellblocks built by inmates starting in 1872.
Good to know
How much does it cost to soak and when is it open?
Day use costs $5 per vehicle or is covered by a valid interagency pass. Hours are strictly enforced from 7 a.m. to 9 p.m., and the gates are locked at night with no overnight camping allowed at the springs.
Are swimsuits required at Kirkham Hot Springs?
Yes. Because the pools sit directly adjacent to a major state highway and a public Forest Service day-use area, swimsuits are strictly mandatory.
How hot are the soaking pools?
Temperatures vary depending on river level and pool position, ranging from comfortably warm in lower riverside pools to around 110°F in the higher pools directly under the cliff source.
Are there restrooms or drinking water on-site?
Vault toilets and changing stalls are available near the parking area, but there is no drinking water and cell service is spotty to non-existent, so pack out your trash and bring your own water.
Plan a visit & invite your people →
Further reading: fs.usda.gov · recreation.gov · islands.com · Reddit
last checked: 2026-06-24