Entry No. 158 — the Denver file — filed under: geothermal caves
Indian Hot Springs Geothermal Caves
Rock caves bored into the mountainside in the early 1900s form pitch-dark, steam-filled grottos where you soak in 108-120F geothermal mineral pools with near-100% humidity dripping off the stone walls — separate caves for men and women, open year-round. The facility is a fully operating historic resort 30 minutes west of Denver with hotel rooms, private baths, an indoor tropical pool, and a BBQ restaurant on-site.
The story
In the 1860s, gold prospectors drilling along Soda Creek kept hitting hot water instead of pay dirt. Frustrated by their 'hot water mine,' they sold the property in 1863 to E.M. Cummings, who quickly realized that selling 'health baths' to filthy miners was more lucrative than digging for gold. By 1866, buyer Harrison Montague erected stone bathhouses and dubbed the property the 'Saratoga of the Rocky Mountains.' Between 1903 and 1911, workers bored deep into the solid granite mountainside specifically to trap the rising geothermal steam, carving out subterranean grottos that look less like a modern wellness resort and more like a secret Victorian bathhouse hidden in a mine shaft.
The water feeding these sunken stone pools bubbles up directly from magma chambers deep below the mountain core. Inside the caves, humidity hovers near 100 percent, hot mineral water drips from the low-hanging granite ceilings, and pitch-dark alcoves stay blanketed in thick steam. Stepping out of the caves puts you in stark contrast with the resort's central atrium—a glass dome housing live banana and palm trees surrounding a large turquoise pool, sitting right at 7,500 feet elevation just off Interstate 70.
Because the caves were blasted out when communal bathing was functional rather than luxurious, they remain strictly gender-segregated and adults-only. You aren't coming here for sleek Swedish spa treatments; you're coming for raw, sulfurous, turn-of-the-century heat trapped in heavy stone chambers where you can barely see three feet ahead through the mist.
What it's like
Expect a nostalgic, retro atmosphere from the minute you pull up Soda Creek Road and enter the motel-style lobby. After paying at the counter, you'll head downstairs into separate men's or women's wings and descend stone steps into dark, steamy rock caverns. The cave pools range from roughly 104 to 112 degrees Fahrenheit—hot enough that most soakers can only stay submerged for 10 or 15 minutes before taking a break on the wet stone benches. Clothing is optional in the same-sex caves on weekdays, but swimsuits are required on weekends, which tend to draw heavy crowds from Denver. For the quietest experience, arrive on a chilly weekday morning when steam rolls off the stone walls and you might have a grotto to yourself, then book an outdoor private tub ahead of time to reunite with your soaking partner.
The move: Arrive on a weekday morning when the caves are least crowded ($35/person), split up for an hour in the men's and women's geothermal caves, then reunite for a soak in one of the outdoor private mineral tubs before grabbing lunch at the on-site Big Kahuna BBQ — the whole visit runs 2-3 hours and doubles well with a stroll through historic downtown Idaho Springs afterward.
📍 Before you go The resort sits just off I-70 at exit 240 in Idaho Springs, roughly 30 miles (about half an hour) west of Denver; follow Soda Creek Road past downtown to the marked entrance and lot. The caves are adults-only and gender-segregated, so a couple splits up to soak — plan to reunite afterward in a private mineral tub, which you reserve ahead in one-hour slots. Swimsuits are required in the public pool, but the same-sex caves are clothing-optional on weekdays. Weekday mornings are calmest; weekends and holidays fill up, so book ahead. It's open year-round, and winter steam in the cold air is part of the appeal. Pair it with a walk through historic downtown Idaho Springs.
- 📍 Idaho Springs
- 💸 $$
- ⚡ Low-key
- 🌗 Indoor or outdoor
Where: 302 Soda Creek Rd, Idaho Springs, CO 80452
Hours: Mined 2026-06-07 — confirm current hours before you go.
Pair it with
- Charlie Tayler Water Wheel — Pair your bath with a quick stop at this 30-foot wooden waterwheel down the street, built in 1893 by a local miner who famously refused to ever bathe.
- Edgar Experimental Mine — Contrast the man-made steam grottos with an authentic hard-rock mine tour down an active research mine run by the Colorado School of Mines less than a mile away.
- Underhill Museum — Walk 0.3 miles into downtown Idaho Springs after your soak to explore a Victorian mining engineer's preserved home and office from the gold rush era.
- Chief Mountain Trail — Tackle this short, high-altitude ridge trail off Squaw Pass Road beforehand so your muscles earn the 110-degree geothermal heat.
Good to know
Do I need to wear a swimsuit in the geothermal caves?
Swimsuits are optional in the gender-segregated caves on weekdays, but mandatory on weekends and holidays. Swimsuits are always required in the main indoor tropical pool.
Are children allowed in the geothermal caves?
No, the geothermal caves are strictly adults-only (ages 18 and older). Families traveling with kids can use the main indoor pool under the tropical glass dome instead.
Can couples soak together in the caves?
No, the geothermal caves are strictly separated into men's and women's grottos. Couples wanting to soak together can reserve an outdoor private cedar tub or an indoor private bath in one-hour slots.
How hot are the cave mineral pools?
The sunken walk-in pools inside the geothermal caves naturally maintain temperatures between 104°F and 112°F with near-100% humidity.
Plan a visit & invite your people →
Further reading: Official site · Yelp · Tripadvisor · Westword · Reddit
last checked: 2026-06-07