Wiesbaden Hot Springs

Under this small Ouray hotel lies one of the most unusual soaks in the Rockies: a natural vapor cave held at about 108°F, which the hotel describes as one of only two commercially operated vapor caves in the United States. You pass through a first chamber where spring water spills over the rock, then into the main cave, where a soaking pool sits in the warm, wet air. Outside, a flow-through mineral pool runs about 100 to 106°F with untreated, non-recirculated water.

The Lorelei, a screened private outdoor pool at 100 to 105°F, is the only clothing-optional spot on the property and needs its own reservation; everywhere else you wear a swimsuit. Day visitors can book two-hour soaks covering both the cave and the outdoor pool, but capacity is small, so call before you come. Children under five are not allowed in the water.

Overnight guests choose from rooms with private baths, suites, a hillside cottage, a small house on the historic register and a three-bedroom home above the property, all with access to the springs. The hotel is at 625 5th Street in Ouray, a few minutes from the town pool if you want a second soak. The downside: the cave is humid and close, which some people find stifling, and with so few spots you may wait for a slot.