Sunflower Hot Springs
By the HotSpringsFind editorial team · How we compile records · Reviewed September 2026
Sunflower Hot Springs is a primitive hot spring listed near Challis (Middle Fork corridor), Idaho. Reported soak temperature: 104°F. See the visit fact sheet.
Current status
The most famous hot spring on the Middle Fork of the Salmon River (~mile 32.6, river right) — terraced rock pools with a hot waterfall shower, in the Frank Church-River of No Return Wilderness; reachable essentially only on a permitted Middle Fork float trip (year-round permit; lottery control season May 28-Sep 3) or a long wilderness hike.
verified against an official source · 5 sources ↓
Before you go
- Status: Reservation or permission required — confirm via Recreation.gov — Middle Fork of the Salmon (4 Rivers) permit page (year-round permit, lottery season May 28-Sep 3, 7 launches/day).
- 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-optional; pets reported not allowed — confirm current rules.
- Conditions: check weather, fire closures, and land-manager alerts the week you go — mountain access changes seasonally.
- Reservations/permits: Middle Fork of the Salmon float permit via recreation.gov (Four Rivers lottery); $6 application + $4/person/day user fee; max trip length 6-8 days depending on group size; Idaho invasive-species boat sticker required.
- Booking: Lottery / limited reservations.
- Best time to go: July-August river season; pools vary with river level and maintenance.
- Clothing reality: No posted policy; mixed custom on river trips — commercial groups typically clothed.
- Cell service: none — download maps and tell someone your plan.
- Accessibility: Not accessible — requires a multi-day wilderness float trip or long hike.
- Float permit REQUIRED year-round to be on the Middle Fork between Dagger Falls and the Main Salmon confluence; lottery control season May 28-Sep 3 (apply Dec 1-Jan 31 on recreation.gov, results Feb 14); only 7 launches/day
- Outside the control season, first-come permits open Oct 1 on recreation.gov — but Boundary Creek access road is snowed out until ~mid-June and the river freezes in winter
- Pools sit just above the riverbank — no real hike, but the approach is slick rock; poison ivy flanks part of the path
- Terraced pools get hotter uphill — the top 'lobster pot' can be too hot; test before entering
- Sunflower camp is small (max ~8 people) — spring is a popular stop for groups camped nearby; share the pools, keep soap out
- No road access at all — alternatives are the ~30+ mile Middle Fork Trail hike or flying to a wilderness airstrip
- River miles cited vary by source: ~32.6 (USFS) vs ~33.6 (guidebook) — same site
- Hazard: Whitewater river trip required for access (Class III-IV)
- Hazard: Slick rocks at pools — falls happen
- Hazard: Poison ivy along the approach
- Hazard: Very hot upper pool ('lobster pot')
- Hazard: Remote wilderness — no services
About this spring
Iconic Middle Fork Salmon River hot spring — small terraced pools overlooking the river ending in a hot waterfall that showers into the current. The classic photo stop of the Middle Fork (river-right ~mile 32.6); reached primarily by permitted float trips. Source ~149°F — soak only in cooled pools. Fee: Middle Fork float permit required in season. Source 149°F causes serious burns — test pools. Poison ivy on the approach; slippery rocks.
Sunflower Hot Springs is the famous photo stop of the Middle Fork of the Salmon River — small terraced pools above the river ending in a hot waterfall that showers straight into the current, river-right near mile 32.6 in the Frank Church–River of No Return Wilderness. The source runs around 149°F, so only the cooled lower pools are soakable — test carefully, and watch for poison ivy and slick rock on the short approach.
Reaching it essentially means floating the Middle Fork, which requires a permit year-round between Dagger Falls and the Main Salmon confluence. During the lottery control season (late May through early September) permits are drawn through Recreation.gov — applications open in December with results in February and only seven launches a day. Outside control season the permit is still required but conditions and river levels rule the trip.
Directions & trailhead access
Float the Middle Fork Salmon from Boundary Creek; spring river-right near mile 32.6, marked by the steaming waterfall.
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-optional |
| Pet policy | Reported no pets |
| Geothermal data reference | NOAA Thermal Springs List (1980 archive) |
| Check land status | Recreation.gov — Middle Fork of the Salmon (4 Rivers) permit page (year-round permit, lottery season May 28-Sep 3, 7 launches/day) |
Sunflower Hot Springs FAQ
Is Sunflower Hot Springs open right now?
The most famous hot spring on the Middle Fork of the Salmon River (~mile 32.6, river right) — terraced rock pools with a hot waterfall shower, in the Frank Church-River of No Return Wilderness; reachable essentially only on a permitted Middle Fork float trip (year-round permit; lottery control season May 28-Sep 3) or a long wilderness hike. (Status verified against an official source.)
Is Sunflower Hot Springs free?
Sunflower Hot Springs 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 Sunflower Hot Springs?
Sunflower Hot Springs has a reported soak temperature of 104°F. Historical data may not reflect current conditions — always test water before entering.
Is Sunflower Hot Springs clothing optional?
Sunflower Hot Springs is listed as traditionally clothing-optional in directory records. Confirm current rules before visiting, as policies change.
How do you access Sunflower Hot Springs?
Sunflower Hot Springs requires permission, a permit or advance booking — confirm the terms with the site manager before visiting.
Sources & references
- Recreation.gov — Middle Fork of the Salmon (4 Rivers) permit page (year-round permit, lottery season May 28-Sep 3, 7 launches/day) — official · 2025
- USFS Salmon-Challis NF — Middle Fork of the Salmon River (permit system, Boundary Creek road snow closure) — official · 2025
- Northwest Rafting — Hot Springs on the Middle Fork (Sunflower mile 33.6, pool details) — operator · 2024
- GoRafting — Sunflower Hot Springs (shower, poison ivy, single-group etiquette) — operator · 2024
- middleforkofthesalmonriver.com — Sunflower camp (USFS mile 32.6, hot springs, poison ivy) — community · 2025
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
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