Wild Willy's Hot Springs - Free soaking · donation encouraged in Mammoth Lakes, CA (2026)
Boardwalks lead to heart-shaped soaking pools in Long Valley with panoramic views of the Glass Mountains. Natural caldera heat keeps the water comfortable even during winter storms.
Wild Willy's Hot Springs is a free, family-doable wild soak in the Long Valley Caldera south of Mammoth Lakes, California — known for its iconic heart-shaped main soaking pool and the wooden boardwalks that protect the surrounding tufa terraces from foot traffic. The water comes from the Long Valley geothermal system that powers the area's commercial geothermal plants, kept around 100°F at the pool by mixing the hot vent water with cold creek runoff. Free, on LADWP land, no permits, dawn-and-dusk are the windows when the parking lot isn't already full.
What to expect
Drive south of Mammoth on Highway 395, turn east onto Benton Crossing Road, follow signs to the parking area. Walk the boardwalk to the heart-shaped pool and a smaller secondary pool. The pools are roomy enough for several groups and the wooden boardwalks let you cross the fragile tufa without damaging it. Clothing-optional in practice. No facilities at all. Best at sunrise on weekdays; weekends fill the parking before sunrise.
Temperature
95°-103°F
Pools
2 soaking pools
Best season
May-October
Reservations
Walk-up friendly
Dog policy
Leashed dogs welcome
Family policy
Family windows available
Safety notes
- Parking lot fills before sunrise on weekends—arrive early or pick a weekday.
- Do not leave cairns or carve initials into the fragile tufa; fines are enforced.
Amenities & etiquette
FAQ
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