Nimrod Hot Springs

Near Byrne, Montana

Verified · 3 independent sources

WATER: hot spring
FALLS: Waterfall on site
ACCESS: Local spot, unofficial
FEE: Free
SEASON: Best in summer

About Nimrod Hot Springs

Nimrod Hot Springs is a free, undeveloped geothermal pool along the Clark Fork River near Byrne, Montana, reached by a short walk from a Fishing Access pullout off I-90 near Bearmouth. It sits on private land where the owning family has informally tolerated public access, and it functions more as a swimming hole than a soaking spring, with a deep turquoise pool, an underwater cave, and cliff-jumping spots.

The spring sits in a small canyon along the Clark Fork River valley, with the pool tucked against a rock wall a short distance from I-90 traffic; multiple sources describe the water as clear and turquoise/blue, fed by a rock cascade coming off the canyon wall.

Swimming at Nimrod Hot Springs

The pool is described as deeper and larger than most Montana hot springs, suitable for actual swimming rather than just soaking, with cliff jumping from multiple heights and a submerged cave passage that sources say should only be attempted by strong, experienced swimmers.

How to get to this swimming hole

From Missoula, take I-90 east to Exit 138 (Bearmouth), head onto Drummond Frontage Road, turn at the 'Fishing Access' sign, and park in the unpaved lot; then walk roughly half a mile west along the old highway grade to the pool.

Parking: Unpaved pullout/lot at a Fishing Access site off Drummond Frontage Road, about 1,500 feet from the start of the walking path; no facilities at the lot.

The hike in

To the water: about 0.5 mile one-way
Time on foot: Roughly 10-15 minutes each way at a casual walking pace.

Difficulty: Easy, flat, level walking surface the whole way with no elevation gain and no river or creek crossings, though the gravel/dirt surface can turn muddy or icy in winter and spring per two independent sources.

Trailhead: Unmarked dirt pullout at a 'Fishing Access' sign on Drummond Frontage Road, reached from I-90 Exit 138 (Bearmouth) near Byrne, MT, not a maintained trailhead, just a wide spot off the frontage road.

This is the entire walk-in, not a segment of a longer marked trail, there is no named hiking trail here, just a 0.5-mile dirt/gravel old highway grade/frontage-road bed running between I-90 and the railroad tracks, ending at a fence line visitors duck under/around to reach the canyon and pool.

Path parallels I-90 traffic and an active railroad line for the full 0.5 mile, so it's noisier than a backcountry trail; sources note being mindful of kids near the highway/tracks. No formal trail markers or signage, route-finding is simply 'follow the old road grade west with the highway on your left' to the fence at the end.

Plan your visit

Bringing kids

OK with supervision

The pool is deep enough for swimming and free-diving (not a shallow wading spot), there's no lifeguard, no cell service in the canyon, and cliff-jumping/an underwater cave passage are present, so several sources say 'keep kids close.' The 0.5-mile walk-in is flat and easy enough for most families, and one aggregator calls it kid-friendly, but supervision around the water is essential given the depth, cold-water-shock risk, and proximity of I-90/the railroad along the access path.

Parking

Free

Informal unpaved parking pullout at a Fishing Access site off Drummond Frontage Road, roughly 1,500 feet from where the walk-in path begins. No lot markings or facilities. Multiple sources warn not to park along I-90 itself, which risks a ticket or tow.

Restrooms

None on site

No restrooms, changing areas, or trash bins at either the parking pullout or the pool itself (confirmed by hotspringsguides.com, discoveringmontana.com, and trywater.club); visitors must be self-sufficient and pack out all trash.

Water clarity

Clear

Every source that addresses clarity describes the pool as crystal-clear and turquoise/blue, with visibility good enough from the surface to gauge the pool's depth. One source attributes the clarity to mineral content plus a continuous rock-cascade inflow from the spring that keeps the pool gently circulating rather than stagnant.

Hours

No official hours; described as free, 24/7 access. Day-use only, at least one source states camping is not permitted.

Swim smart

No lifeguard or rescue infrastructure; limited to no cell phone service in the canyon; cold-water shock risk despite the pool's modest warmth; drowning risk from pool depth; the underwater cave passage is flagged as dangerous for inexperienced swimmers; cliff jumping requires checking water depth first, as levels fluctuate seasonally; approach trail can be slippery when muddy or icy.

Rules: The pool and immediate surroundings are on private land (attributed to the Czorny family by two sources); public access is informally tolerated rather than officially granted. Visitors are asked to follow Leave No Trace practices, pack out all trash, stay on established routes, and respect posted private-property/trespass boundaries; one source states day-use only with no camping permitted.

This is an informational listing, not an invitation. Conditions and access change; verify locally before you go. Visiting any swimming hole is at your own risk. See our Terms of Use.

On the water

Restrictions: The swimming pool itself is a small, enclosed geothermal pocket set beside (not directly in) the Clark Fork River's main current, it is not a boat launch or a floatable stretch, and no source mentions kayaks, canoes, or paddleboards being used at the pool.

The Clark Fork River runs immediately below/adjacent to the pool and is floatable elsewhere in the valley (rafting/fishing country), but nothing found describes launching watercraft at this specific access point or carrying a boat down the 0.5-mile walk-in.

Rentals nearby

The Trail Head

Canoes, rafts, kayaks, stand-up paddleboards (SUPs), and river accessories (helmets, dry bags, PFDs) for floating area rivers, marketed under their 'Trail Head River Sports' line

221 E Front St, Missoula, MT, the nearest general river-outfitter, roughly 35-40 miles west of Nimrod Hot Springs; not specific to this exact access point

What regulars say

Visitor accounts of Nimrod Hot Springs are informal but consistent: repeated warnings to pack out all trash because the private landowner (the Czorny family) has previously tolerated access only informally and could close it; advice to avoid geotagging or heavily promoting the spot online to limit crowding; it gets busiest on summer weekends, with mornings and the September shoulder season noted as quieter; and winter/spring visitors should expect a muddy or icy 0.5-mile walk-in.

Nimrod Hot Springs: FAQ

Does Nimrod Hot Springs charge a fee?

Free; no tickets, reservations, or opening hours.

Is Nimrod Hot Springs kid friendly?

How hard is the hike to Nimrod Hot Springs?

A hike is required, about about 0.5 mile one-way to the water (roughly 10-15 minutes each way at a casual walking pace.). Wear real shoes, since approaches to natural swim spots are often rocky or rooty.

Where do I park for Nimrod Hot Springs?

When is the best time to visit Nimrod Hot Springs?

Late June through September (summer) is most commonly cited as ideal; the approach trail can be muddy or icy in winter and spring, and road/trail access can be affected by spring snowmelt or heavy rain.

What are the rules at Nimrod Hot Springs?

The pool and immediate surroundings are on private land (attributed to the Czorny family by two sources); public access is informally tolerated rather than officially granted. Visitors are asked to follow Leave No Trace practices, pack out all trash, stay on established routes, and respect posted private-property/trespass boundaries; one source states day-use only with no camping permitted.