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.
Rocky Canyon Hot Springs is a series of tiered, user-built pools on the far bank of the Middle Fork of the Payette River, north of Crouch, Idaho. Reaching them requires a cold ford of the river; the pools are best after spring runoff.
Miracle Hot Springs is a hot springs resort near Buhl, Idaho, on Highway 30 south of Hagerman, with multiple large general admission geothermal pools plus many private hot pools with adjustable temperatures. General admission starts at $14, private pools from $10, and VIP pools from $25.
Pine Flats Hot Springs is a string of natural hot pools beside the South Fork of the Payette River near Lowman, Idaho, reached by a 0.25 to 0.75-mile hike from Pine Flats Campground. The pools are usable all winter.
Campground Hot Springs is a roadside soak on the South Fork of the Payette River, across the Banks-Lowman Highway from Hot Springs Campground east of Garden Valley, Idaho. Its main rock-lined pool runs about 110°F, reached by a staircase from the road.
Little Anderson Hot Springs, near Garden Valley, Idaho, was once a stellar, locally kept soak in the Boise National Forest. Today the pool and primitive sites are heavily damaged by ATV use and trash; visit with low expectations.
Roystone Hot Springs is a reservation-only hot springs, RV park, and event center in Sweet, Idaho, about 45 minutes from the Treasure Valley. Every soak is private to the reserving group; the pool runs 93–98°F and the jetted hot tub about 104°F.
The Springs is a hot springs resort on Highway 21 near Idaho City, Idaho, with a 40′ x 80′ geothermal pool, a 104° hot tub, a steam room, massage services, and private tubs. Soak sessions run $30 for adults and $27 for children; reservations are required.