Loon Creek Hot Spring
By the HotSpringsFind editorial team · How we compile records · Reviewed September 2026
Loon Creek Hot Spring is a primitive hot spring listed near Challis, Idaho. Reported soak temperature: 104°F. See the visit fact sheet.
Current status
The largest hot-spring pool on the Middle Fork of the Salmon (deep tub fitting ~10, a few steps from cold Loon Creek) sits ~0.5-1 mile up Loon Creek Trail at river mile ~49-50 inside the Frank Church wilderness — there is no road; you reach it by permitted Middle Fork float trip (recreation.gov lottery May 28-Sep 3), by flying to the Lower Loon backcountry airstrip (20-min walk), or by a ~15-mile backpack down Loon Creek Trail.
Checked September 2026 · verified against an official source · 7 sources ↓
Before you go
- Status: Reservation or permission required — confirm via Recreation.gov — Middle Fork Of The Salmon permit page (year-round permit; lottery control season May 28-Sep 3; 7 launches/day; fees; hot springs noted as feature).
- Cost: Reported free access — fees and permits can change, confirm before visiting.
- Getting there: No verified hike distance on record — confirm the route and road conditions.
- Water: Reported soak temperature 104°F — always test the water before entering.
- Rules: Reported clothing required; reported dog-friendly.
- Conditions: check weather, fire closures, and land-manager alerts the week you go — mountain access changes seasonally.
- Reservations/permits: Middle Fork float permit required year-round (recreation.gov permit 234623); May 28-Sep 3 launches allocated by lottery (apply Dec 1-Jan 31); $6 reservation fee + $4/person/day recreation fee; commercial outfitters hold their own allocations. Day hikers from the airstrip or Loon Creek Trail need no permit but must follow wilderness + river-corridor rules (human waste pack-out within 1/4 mi of river).
- Booking: Lottery / limited reservations.
- Best time to go: Float season late May-early Sept (controlled); rafters hit the pool midday/evening — early morning soaks are quietest. Fall (post-Labor Day) trips get springs and camps to themselves. Road/trail access July-Oct; spring itself flows year-round but is essentially unreachable in winter.
- Clothing reality: No posted policy; swimsuits are the norm — the pool is shared with other rafting groups and sits on a popular trail, so discreet clothing-optional use is not customary here.
- Kids: Allowed.
- Cell service: none — download maps and tell someone your plan.
- Accessibility: Backcountry only — minimum ~0.5-1 mi of rough trail with a steep final pitch, plus either a multi-day river trip, a bush flight, or a 15+ mi backpack.
- NO ROAD ACCESS — inside the Frank Church-River of No Return Wilderness; there is no drive-to option despite some directory listings implying otherwise
- Standard visit = Middle Fork float trip: float permit required YEAR-ROUND (recreation.gov 'Middle Fork Of The Salmon'); control-season launches (May 28-Sep 3) are lottery-only — apply Dec 1-Jan 31; ~387 launches for thousands of applicants; only 7 launches/day; $4/person/day recreation fee
- Fly-in option: Lower Loon airstrip (C53, Idaho Fish & Game) is ~20-min walk from the springs — skilled backcountry pilots only; charter from Boise/Stanley/McCall
- Hike-in option: Loon Creek Trail from the end of rough 4x4 Loon Creek Road #007 (Tin Cup CG/Upper Loon airstrip) is ~15+ miles one way; road itself is seasonal high-clearance over Loon Creek Summit
- From river: spring is ~0.5-1 mi up Loon Creek from Big Loon Camp (mile 49.3) — trail leaves the back of camp, crosses a bridge, then a short steep unsigned path veers left to the creek; easy to miss; leave stock gates as you find them
- Wild & Scenic river-corridor rules within 1/4 mi of the river: pack out ALL waste including human (porta-potty required on float trips), fires only in fire pans, no mechanized equipment
- Source water ~120F (USGS 1980 sampling) — the big pool soaks fine but test the inlet side; polar-plunge in cold Loon Creek is the standard rotation
- Source is on a private-ranch-adjacent trail corridor near the Middle Fork Outfitters/Middle Fork Lodge inholding — respect fences, gates and private buildings
- Hazard: Extreme remoteness — wilderness canyon, no cell, help is hours-to-days away
- Hazard: Hot source ~120F at inlet — test before stepping in
- Hazard: Whitewater environment (Class III-IV Middle Fork) — drowning risk; cold-water creek
- Hazard: Rattlesnakes, black bear, poison ivy along the trail/river corridor
- Hazard: Downfall/rockfall on Loon Creek Trail; spring flooding covers trail segments
- Hazard: Wildfire closures are common in this drainage in late summer
About this spring
A large creekside soaking pool (~10-person capacity) on Loon Creek about a mile up from its confluence with the Middle Fork of the Salmon River, in the Frank Church-River of No Return Wilderness. One of the best-known hot spring stops on Middle Fork rafting trips; cold plunge in the creek a few steps away. Remote wilderness. Middle Fork float permits required in control season. Source ~120°F — scalding. No drive-up access.
Loon Creek Hot Spring is the marquee soak of the Middle Fork of the Salmon River corridor — the largest-capacity pool on the run, holding roughly ten soakers beside the creek about a half-mile up from the confluence camps. Sitting at river mile 50.1 inside the Frank Church-River of No Return Wilderness, it isn't technically on the river at all: boaters tie up near the mouth and hike upstream past a backcountry cabin, and the cold creek a few steps away serves as the 'polar plunge' between rounds.
The spring is reachable on foot from four river camps — Loon and Cow downstream of the creek, Shelf and White Creek upstream — and sees steady traffic on permitted Middle Fork floats, where Forest Service rules limit groups to one hot-spring camp per trip and prohibit soap and nudity at the springs.
Directions & trailhead access
Most visitors arrive on permitted Middle Fork float trips — hike ~0.5-1 mi up Loon Creek from the confluence camps. Overland: long rough high-clearance roads to the Loon Creek Guard Station area, snow-closed in winter.
Idaho geothermal context
Idaho's thermal water rides the old track of the Yellowstone hotspot across the Snake River Plain and surfaces along faults in the surrounding mountains. Many of the best soaks are roadside or river-access pools inside national forests — including springs that only emerge when river levels drop. Backcountry sites demand real navigation skills and long dirt-road drives.
What a primitive site means here
Primitive springs have no facilities: no changing rooms, no trash service, often no maintained road to the pool. Expect natural rock or gravel bottoms, water temperature that varies by spot and season, and other visitors who may treat the site informally. Pack out everything you bring, test the water before entering, and leave the pool cleaner than you found it.
Best time to visit
Year-Round (Best: May – October)Pool temperatures and access can change with weather and season. Outdoor ambient temperatures fluctuate significantly across Idaho. Late spring through autumn offers the most comfortable road access.
Fact sheet
| Reported soak temp | 104°F |
|---|---|
| Source temp (historical) | Not reported |
| Trail access | Recorded coordinates — access unverified |
| Access fee | Reported free — verify locally |
| Clothing policy | Reported clothing required |
| Pet policy | Reported dog-friendly |
| Geothermal data reference | NOAA Thermal Springs List (1980 archive) |
| Check land status | Recreation.gov — Middle Fork Of The Salmon permit page (year-round permit; lottery control season May 28-Sep 3; 7 launches/day; fees; hot springs noted as feature) |
Loon Creek Hot Spring FAQ
Is Loon Creek Hot Spring open right now?
The largest hot-spring pool on the Middle Fork of the Salmon (deep tub fitting ~10, a few steps from cold Loon Creek) sits ~0.5-1 mile up Loon Creek Trail at river mile ~49-50 inside the Frank Church wilderness — there is no road; you reach it by permitted Middle Fork float trip (recreation.gov lottery May 28-Sep 3), by flying to the Lower Loon backcountry airstrip (20-min walk), or by a ~15-mile backpack down Loon Creek Trail. (Status verified against an official source, last checked September 2026.)
Is Loon Creek Hot Spring free?
Loon Creek Hot Spring is listed as free to access in Custer County, Idaho. Fees and rules change — verify current status with the land manager before visiting.
What temperature is Loon Creek Hot Spring?
Loon Creek Hot Spring has a reported soak temperature of 104°F. Historical data may not reflect current conditions — always test water before entering.
Is Loon Creek Hot Spring clothing optional?
Loon Creek Hot Spring is listed as swimsuit-required in directory records. Confirm current rules before visiting, as policies change.
How do you access Loon Creek Hot Spring?
Loon Creek Hot Spring is on public land — verify current road access, fees and rules with the land manager before visiting.
Sources & references
- Recreation.gov — Middle Fork Of The Salmon permit page (year-round permit; lottery control season May 28-Sep 3; 7 launches/day; fees; hot springs noted as feature) — official · 2026-09
- USFS Salmon-Challis NF — Middle Fork Region / Loon Creek Area MF2 (roads, wilderness rules, seasonal closures) — fs.usda.gov blocks direct fetch; text via search index — official · 2026-09
- Northwest Rafting Co. — Hot Springs on the Middle Fork (Loon Creek at mile 50.1; ~0.5-mi walk; fits ~10; hikeable from Loon/Cow/Shelf/White Creek camps) — operator · 2025
- Idaho River Journeys — Middle Fork Salmon River Hot Springs (largest hot spring pool on the Middle Fork; ~1 mi up Loon Creek) — operator · 2025
- shortfield.com — Lower Loon Creek airstrip C53 (IDFG strip; hot springs ~20-min walk up Loon Creek trail; Big Loon Camp nearby) — community · 2024
- GoRafting.com — Loon Creek Hot Springs (trail beta from Big Loon camp: bridge, gates, easy-to-miss steep side path) — community · 2023
- soakingsprings.com — Lower Loon Creek Hot Spring (44.799,-114.806; 120F source; USGS 1980 sample; 'open' access) — used for lead/data cross-check only — community · 2026-08
Details above were verified against the named sources on their listed dates — conditions change, so recheck before traveling. · How we verify our data · Report a correction
Your private trip notes
Saved only in this browser — not published or shared.No private notes yet
Keep access details and observations for your own planning.