Spas with moderate

Vail, Colorado

Hotel spa and recovery club in Vail Village with hot tubs, cold plunge, sauna, salt room and a gym, open to day-pass visitors.

Krynica-Zdrój, Lesser Poland

Mountain resort spa in Krynica-Zdrój with indoor and outdoor pools, a sauna complex, and a clothing-optional 18+ zone; day passes available.

Palm Springs, California

A 16-room adults-only hotel in Desert Hot Springs with three natural mineral-water pools fed by a 350-foot geothermal well, plus a small on-site spa and

Rogaška Slatina, Savinjska

Wellness center at Grand Hotel Rogaška in Rogaška Slatina, Slovenia, with pools, saunas and fitness; day pass available by reservation.

Brežice, Posavje

A large thermal water park in Brežice, Slovenia, with a year-round indoor pool riviera, an adults-only sauna zone, and seasonal outdoor slides.

Carson, Washington

A clothing-optional, adults-only mineral hot springs bathhouse in Carson, Washington, with a $12 day pass and a $30 bath-and-wrap treatment.

Lake Tahoe, California

A resort spa inside Granlibakken's mountain lodging complex near Tahoe City, open to hotel guests with a pool, hot tub and yoga space on site.

Palm Springs, California

A 10-room mineral hot springs hotel in Desert Hot Springs near Palm Springs, offering day passes to its 120°F spring-fed pools, sauna and massage rooms.