South-Central Idaho holds the deepest bench of hot springs in the state, stretching from the Boise National Forest and the Sawtooth Mountains down to the Snake River plain. River soaks like Kirkham, Bonneville and Pine Flats line the Payette River canyons north of Boise, backcountry pools hide along the Middle Fork of the Boise River and around Stanley and Atlanta, and developed resorts, including Miracle and Banbury near Buhl, The Springs in Idaho City and Silver Creek Plunge, make soaking easy in any season. Winter access varies sharply with elevation: low canyon pools can be reached year-round, while high forest roads close with snow until late spring.
Ninemeyer Hot Springs is a late-season-only proposition on the far side of the Middle Fork Boise River: rocky, user-built pools with sand and rock bottoms that sit submerged or unreachable for most of the year. The access window is small — fording the river is only advised at low water, usually late July through November — and on multiple documented visits the pools were only ever seen steaming from the wrong side of a swollen river.
Loftus Hot Springs is a pair of user-built rock pools along the Middle Fork Boise River Road — famous, heavily used, and with a rough recent history: the pools were destroyed by vandals in 2011 and rebuilt by local soak seekers, in reduced form, later that year. The upper pool (102°F, mortar-reinforced) and lower pool (100°F) sit right off the washboard road between Boise and Atlanta, and usage here is extreme — this is a known party spot for hunters and ATVers, kegs and all. Two cautions from the listing itself: watch for broken glass in the pools, and poison ivy grows around them.
Granite Creek Hot Springs is a seasonal riverside soak right next to the Middle Fork Road in the Atlanta area — a set of rock-walled pools with sand, gravel, and rock bottoms at the edge of the Middle Fork Boise River. Finding the right spot can be tricky: there may or may not be a pool ready depending on when you visit, and the pools that exist swirl hot and cold water together, so a good soak takes a little work.
Roaring River Hot Springs — also known as Dutch Frank — is a sprawling geothermal complex where the Roaring River meets the Middle Fork Boise River in the Boise National Forest’s Mountain Home District. Heat emanates from multiple spots along the river, and roadside rock-walled pools appear wherever soakers have dug them. It’s a prospector’s soak: there may or may not be something worthwhile ready when you arrive, but the opportunity is everywhere.
Chattanooga Hot Springs is one of the finest natural soaks in the Atlanta area: a large, shallow, waterfall-fed pool beside the Middle Fork Boise River near the town of Atlanta, Idaho. The catch is timing — depending on how strong spring runoff runs, the pool can sit submerged in the river. Come late season, when the river drops, and this 102°F soak is tough to beat. Red spider mites have been reported here, so keep gear off the rocks.
Browns Creek Hot Springs hides on the far side of the Middle Fork Boise River in the Atlanta area — and the river is the gatekeeper. A deep, cold ford that should only be attempted at low water (usually August) guards a small set of shallow seasonal pools, a roughly 30-foot hot waterfall shower, and one secret two-person rock-and-mortar soaker tucked into a nook in the rocks, the only pool out of view of the road.
Atlanta Annex 1 & 2 are two undeveloped hot springs along the road near Atlanta, Idaho, sitting between three of the best soaks in the area — Atlanta, Chattanooga, and Powerplant. Each has a large pool with enough hot water flowing to support development, but they remain unbuilt, highly visible from the road, and frankly outclassed by their neighbors.
Atlanta Hot Springs is the hometown soak of Atlanta, Idaho: one large rock-and-mortar pool with benches and piped-in hot and cold water, in the Boise National Forest near the old mining town. It is wildly popular with locals — expect company, and expect it to be used hard. One caution is documented right on the listing: red spider mites inhabit this hot spring, so keep clothing and towels off the rocks.
Deadwood Hot Springs is a true jewel of the Boise National Forest: three pools — two small, one a large cliff-hanger soaker on a granite ledge above Warm Springs Creek — at the end of an approximately 3-mile hike from Deadwood Reservoir, northwest of Lowman, Idaho. The sources emerge through fissures all over a huge granite outcropping rising straight out of the creek.
Upper Loon Hot Springs is a complex of four separate hot spring sources strung along the Loon Creek Trail in the Frank Church–River of No Return Wilderness, passed in consecutive order as you trek up Loon Creek toward Warm Springs Creek. With everything from a two-person soaker to a 10–15 person pool fed by a hot waterfall, it’s one of the finest backpacking soaks in Idaho — reachable only in a short summer-to-fall window.