The Idaho hot springs road trip — 63 open soaks, one giant loop

The numbers: why Idaho is the hot spring capital

A few figures that explain why this state gets its own road trip:

• 67 springs — the most of any state: more than Colorado (36) and Oregon (29) combined.
• 36 free (39 mapped). No other state is close — and three of the mapped free springs are currently closed, so 36 is the soakable count. Free here doesn't mean a ditch by the highway, either: it includes hike-in canyon pools and riverside soaks people plan vacations around.
• 39 primitive/backcountry, 19 resort/spa, 9 community pool. The split tells you what Idaho is: mostly wild, with real resorts where the towns are.
• Temperatures run 82–185°F across the 63 springs with recorded data. Bonneville Hot Springs averages 185°F — the hottest in the state and one of the hottest in the country. It's free, primitive, and a short walk from the road.
• 41 springs sit on paved roads. 15 of those are also free, which is the combination that makes a road trip actually pleasant.
• Two clothing-optional springs: Weir Creek Hot Springs (117°F, free, a short walk from the road near Kooskia) and Jerry Johnson Hot Springs (118°F, free, about 1.3 miles on foot off Highway 12), both in the north. If that's your scene, that's the whole list — plan accordingly, and read our clothing-optional etiquette guide first.
• 43 Idaho springs qualify as winter-accessible in our analysis — open, averaging at least 100°F, within a quarter mile of a drivable road. See the winter hot springs guide if you're doing this loop in the snow.

Leg 1: The central mountains — Boise to Salmon

This is the classic Idaho hot spring corridor, following the Payette and Salmon river canyons north from Boise. Do it in 3–4 days.

Start in Boise and head northeast on Highway 21 toward Idaho City. Your first stop is Bonneville Hot Springs (185°F average, free, primitive, short walk) — the hottest spring in the state. A warning that applies to the whole trip: 185°F water will scald you. The soakable pools are the ones where the hot flow mixes with the creek, and they shift with the season. Check the water with a thermometer before you get in, and skip any pool you can't check safely — skin contact with water this hot can scald in seconds.

Continue to Lowman for Kirkham Hot Springs — 149°F average, a short walk, rated 4.7 across 912 reviews, one of the most-reviewed wild springs in the state. Kirkham sits right along the South Fork of the Payette, and the riverside pools are the reason people detour here.

From Lowman, Highway 21 climbs over Banner Summit into the Stanley Basin. Stop at Sunbeam Hot Springs (108°F, free, primitive, paved road) on the Salmon River — roadside, easy, and a good leg-stretcher. Stanley itself hosts Mountain Village Hot Spring (100°F, resort), rated 4.7 — the Sawtooth backdrop does half the work.

Push north to Salmon for the trip's signature hike: Goldbug Hot Springs (113°F, free, primitive, rated 4.7 across 547 reviews). The trail climbs steeply out of the canyon — it's the "earn your soak" archetype, and our hike-in guide covers what the walk demands. Go on a weekday morning if you can; the pools are small and the word is out.

Leg 2: The southeast — Lava to Almo

Drive south and east from Salmon (or start a separate weekend from Pocatello) for Idaho's resort belt.

Lava Hot Springs (113°F, rated 4.7 across nearly 7,000 reviews) is the most-reviewed spring in the state by an order of magnitude — a full developed complex in a small town that exists largely because of the water. It's the easy, family-friendly counterpoint to Leg 1's backcountry.

From Lava, work the small towns south: Downata Hot Springs in Downey (109°F, $$, resort, paved road) and Maple Grove Hot Springs in Thatcher. Then swing west to Almo for Durfee Hot Springs — 4.7 stars across 173 reviews, a community-pool-style soak at the edge of the City of Rocks country. Pair it with the national reserve if you're making the drive.

Also in this quadrant: Roystone Hot Springs near Sweet (4.7, 904 reviews) — a developed soak that locals treat as a regular habit rather than a destination, which is usually the best review a spring can get.

Leg 3: The north — Idaho County and Kooskia

The northern leg is the wildest and the least forgiving, which is exactly the appeal.

Jerry Johnson Hot Springs (118°F, free, primitive, clothing-optional by long-standing custom) sits about 1.3 miles on foot off Highway 12 along the Lochsa River — an easy walk by Idaho standards, and the riverside pools are excellent. Nearby Stanley Hot Springs (120°F, free, primitive) requires more commitment on foot.

Finish at Weir Creek Hot Springs (117°F, free, primitive, short walk) — one of the state's two clothing-optional springs, with Jerry Johnson. It's a short walk from the road, which makes it accessible, and the etiquette expectations are real: towels, consent, and no cameras, per our etiquette guide.

The free-soak strategy

Idaho's free count deserves its own planning section, because 36 free springs is a trip-planning superpower. The practical version:

• 15 free springs sit directly on paved roads — including Frenchman's Bend near Ketchum (124°F) and Sunbeam. These are your zero-effort stops.
• 24 free springs are paved-road or short-walk access. If you're willing to walk a few minutes from the car, free soaking is the default, not the exception.
• The paid springs earn their keep where access or amenities matter: Lava for the full resort experience, Downata and Mountain Village for developed pools with services, Durfee for the small-town community soak.

One honest note: "free" in our data means no admission fee at the spring itself. It doesn't cover gas, the Forest Service roads, or the fact that the free pools with the best reputations (Goldbug especially) reward early arrival.

Practical notes for the Idaho loop

• Distances are big. The three legs are separated by multi-hour drives — this is a 7–10 day loop done properly, or three separate long weekends. The legs above are designed to stand alone.
• Roads close. Highway 21 over Banner Summit and the high forest roads around Stanley are seasonal. Our winter guide's access-road warning applies double here: "within a quarter mile of a drivable road" is a summer promise. Check Idaho 511 and the relevant national forest's closure maps before a shoulder-season trip.
• Water temps are averages. Bonneville's 185°F and Kirkham's 149°F are dataset averages — the pool you step into depends on flow, season, and how much creek water is mixing in. Scalding-hot sources next to soakable pools is the Idaho norm, not the exception. Check every pool with a thermometer before you get in.
• Leave-no-trace is load-bearing here. 39 of 67 springs are primitive. Pack out everything, stay on durable surfaces around the pools, and don't build new rock dams — the next visitor's soak depends on it.
• What to bring depends on the leg: the packing guide covers the backcountry kit, and the etiquette guide covers the rest.

Start with the Idaho state guide for the full 67-spring list, and use the road-trip planner to string your picks into a route.