At 165°F, the source water at Casa Diablo Hot Pool is hot enough to cause burns. Some hot springs this hot have cooler side pools or downstream areas suitable for soaking — always test the water temperature before entering.
Casa Diablo Hot Pool reaches an intense 165 degrees Fahrenheit at 7,070 feet elevation in the Long Valley Caldera near Mammoth Lakes. This geothermal feature flows approximately 119 degrees above ambient temperature on land owned by the Los Angeles Department of Water and Power.
The pool sits just 155 feet from road access in the eastern Sierra Nevada, accessible by a brief walk through alpine terrain. The immediate landscape shows evidence of active geothermal features, with mineral-stained rocks and steam vents, all set against the backdrop of high-elevation mixed conifer forests with significant winter snowpack exceeding 83 inches annually.
History of Casa Diablo Hot Pool
Casa Diablo occupies the Long Valley Caldera, one of California's most significant geothermal systems. The spring's chemistry—with 1,230 mg/L total dissolved solids, high sodium (350 mg/L), and elevated sulfate and chloride—reflects the intense water-rock interaction in this active volcanic environment.
Park at the roadside pullout and enjoy a brief walk to viewing areas. The spring is extremely hot; observe from safe distances and never attempt immersion. Best visited July through September when high-altitude snow clears; winter access may be limited. Sherwin Creek Campground provides nearby overnight options.|
Is Casa Diablo Hot Pool worth visiting?
Best for
Observing powerful hot springs
Overnight camping trips
Mineral-rich therapeutic bathing
Not ideal for
Casual soaking
Casa Diablo Hot Pool is well suited for observing powerful hot springs and overnight camping trips.
Monthly Climate
30°Jan
28°Feb
33°Mar
39°Apr
47°May
60°Jun
67°Jul
66°Aug
60°Sep
49°Oct
38°Nov
28°Dec
Annual Precip: 16.2 inAnnual Snow: 83.6 in
Best Time to Visit
FebruaryAir 28°F · Water 165°F · +137° contrast
DecemberAir 28°F · Water 165°F · +137° contrast
JanuaryAir 30°F · Water 165°F · +135° contrast
February offers 39°F more contrast than July
USGS Field Measurements
Recent Temperature
189.9°F
(87.7°C)Measured Apr 15, 1992
Water ChemistrySampled 1992-04-15
The water at Casa Diablo Hot Pool is slightly alkaline (pH 7.7) with 1230 mg/L total dissolved solids. It is notably rich in sodium (supports circulation and skin hydration), chloride (natural antiseptic with skin health benefits), and total dissolved solids (higher mineral concentration for therapeutic soaking).
Overview
Sherwin Creek Campground is located in the eastern Sierra Nevada Mountains within 2 miles of the full-service community of Mammoth Lakes, California. Popular among anglers, hikers, off-road vehicle enthusiasts and photographers, the campground is near some of the most spectacular wilderness and outdoor recreation areas in the Sierras.Recreation
With a motocross track and trails, Sherwin Creek is a hot spot for off-road vehicle enthusiasts. The area's majestic scenery and challenging...
What is the water temperature at Casa Diablo Hot Pool?
Casa Diablo Hot Pool has a water temperature of 165°F (74°C). This is considered a hot spring, well above body temperature.
Where is Casa Diablo Hot Pool located?
Casa Diablo Hot Pool is located in Mono County, California at 7,070 feet elevation, near Mammoth Lakes. Coordinates: 37.6470°N, 118.8590°W.
How do I get to Casa Diablo Hot Pool?
Casa Diablo Hot Pool has Short Walk road access (508 ft from the road).
Is Casa Diablo Hot Pool free to visit?
Casa Diablo Hot Pool has Open access. It is managed by CITY.
Can I camp near Casa Diablo Hot Pool?
Yes, Sherwin Creek is located nearby (4.5 miles away).
What minerals are in the water at Casa Diablo Hot Pool?
Water chemistry analysis shows the presence of pH, Total Dissolved Solids, Calcium, Magnesium, Sodium, Sulfate, Chloride, Iron. The pH is 7.7 (slightly alkaline). Total dissolved solids measure 1,230 mg/L.
Is it safe to soak at Casa Diablo Hot Pool?
The water at Casa Diablo Hot Pool reaches 165°F, which can cause severe burns. Do not enter the source pool directly — look for cooled side pools or downstream areas where the water has cooled to a safe temperature. Always tell someone your plans before visiting remote hot springs.
Is Casa Diablo Hot Pool crowded?
Casa Diablo Hot Pool sees varying levels of visitors depending on the season and day of the week.
What should I bring to Casa Diablo Hot Pool?
Essentials for Casa Diablo Hot Pool: swimsuit, towel, water bottle, camping gear, a trash bag to pack out what you pack in. The water is over 110°F — test the temperature before entering and watch for scalding near the source.