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.
Worswick Hot Springs spreads hot water all over a hillside in the Sawtooth National Forest, in the Fairfield/Smoky Mountains area: a variety of log- and rock-dammed pools — including a big log-dammed pool on the hill and a culvert pool below the road — with temperatures that vary by pool and by season. Come late in the season and take your pick.
Skillern Hot Springs is one of the finest backcountry soaks in the Smoky Mountains: a solid rock-walled, waterfall-fed pool with a log dam, reached by a roughly 2-hour hike in the Sawtooth National Forest in the Fairfield/Featherville area. Crystal-clear water at 100–106°F, a trailhead campground, and seasonal riverside pools below make it worth every step.
Preis Hot Springs is a tiny roadside soak in the Sawtooth National Forest, in the Fairfield/Smoky Mountains area: a small sunken wooden box, just a few feet from a seasonally busy forest road, holding clear 102°F water. It barely fits two people — nice and snug — and that’s most of its charm.
Pine Burl Hot Springs is a single rock-walled pool at the end of a 2-mile hike in the Boise National Forest north of Crouch, on the Middle Fork of the Payette River trail — past both Moondipper and Lil Dipper. It’s generally the best soak of the three on this creek, with one quirk: its temperature, usually a near-perfect 101–103°F, can vary dramatically.
Moondipper Hot Springs is a single rock-walled pool on a 2-mile hike along the Middle Fork of the Payette River from the Boiling Springs Guard Station, in the Boise National Forest. It’s the lesser sibling of nearby Pine Burl — a good soak in its narrow window, because Moondipper only works when there’s enough cold creek water to tame a source that runs far too hot on its own.
Wild Rose Hot Springs — better known to many Idaho soakers as Milford Sweat (and filed in the old listings as Milford Sweet) — is a black lava rock pool on BLM land near Carey, Idaho. The pool itself is a good size and the water runs clear, but the old listing is blunt about the downside: this heavily used roadside soak has a severe, long-documented trash problem.
Indian Bathtub II Hot Springs — also listed as Lower Indian Bathtub — is a pair of rock-walled pools on the Bruneau River near Bruneau, Idaho. The scenery is first-rate and the 93–96°F water is inviting, but go in with eyes open: this pretty canyon soak has a documented trash problem, and the access road can defeat anything without clearance and four-wheel drive.
Bronco Billy Hot Springs — also known as Deer Creek — is a cautionary tale along the Banks-Lowman Highway in the Boise National Forest, in the Banks/Garden Valley area. The honest summary: the source pool is far too hot to soak, and the second pool below the highway has been gone since a 1996 mudslide. Most visitors look, and keep driving.
West Pass Hot Springs is a trio of bathtubs soaking beside West Pass Creek in the Sawtooth National Forest, near Clayton on the East Fork of the Salmon River. It’s a quirky, low-use soak — clear, lime-tinted, moderately sulfurous water in plain tubs, in a white-rock canyon that sees very few visitors.
Bowery Hot Springs is one of Idaho’s most unusual soaks: the “pool” is an old fiberglass spa set beside the East Fork of the Salmon River in the Sawtooth National Forest, near Clayton. There is no natural rock pool here — just an aging spa tub, strong sulfur water, big scenery, and (usually) nobody else around.