Spas with thermal pool

Calistoga, California

A clothing-optional hot springs retreat outside Calistoga with eight mineral pools, spa bodywork, and day-pass, camping, and lodging options.

Los Baños, Laguna

A natural spring resort near Mount Makiling in Calauan, Laguna, with outdoor pools, forest trails, and day passes offered every day of the week.

Cancún, Quintana Roo

A boutique hotel near Cancún airport with a small wellness wing — pool, jacuzzi, sauna, steam room and temazcal — open to day-pass visitors.

Thermopolis, Wyoming

Free public bathhouse in Thermopolis, Wyoming, with indoor and outdoor mineral soaking pools held at 104°F, open seven days a week.

Calistoga, California

A historic hot-springs resort in Calistoga with an early-1900s mineral pool, mud baths, and a public restaurant, but spa access is limited to hotel guests.

Austin, Texas

Adults-only resort spa on Lake Austin offering all-inclusive overnight stays and limited day passes to pools, saunas, steam rooms and lake activities.

New Orleans, Louisiana

Hotel spa and rooftop wellness deck in New Orleans' CBD with sauna, steam, cold plunge and thermal circuits, restricted to guests 21 and up.

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.

Karjalohja, Uusimaa

Lakeside resort spa on Lohjanjärvi in Karjalohja, about an hour from Helsinki, with a day pass, thermal pool, salt room and restaurant.

San Miguel de Allende, Guanajuato

A Saturday-only hot springs day spa near San Miguel de Allende with outdoor thermal pools and walk-in access.

Miami, Florida

Hotel spa deck in downtown Miami with sauna, steam room, cold plunge and thermal pools overlooking Biscayne Bay, day passes from $50.

Hudson Valley, New York

Resort spa at Mohonk Mountain House with a steam room, sauna and outdoor heated mineral pool, open to overnight guests and day-pass visitors.

Bangkok

Hotel spa at SO/ Bangkok on Sathorn Road offering facial, body and beauty treatments plus rooftop infinity pool and fitness access, hotel guests only.

Shibu Onsen, Nagano

A ryokan in Shibu Onsen with indoor and outdoor hot-spring baths fed by two blended mineral springs, open only to overnight guests.

Scottsdale, Arizona

A luxury resort spa in Paradise Valley near Scottsdale with outdoor baths, a thermal pool and a relaxation lounge, open to hotel guests only.

The Hamptons, New York

Adults-only destination spa and 12-room retreat in Water Mill, offering hydrotherapy, yoga, spa treatments and overnight stays by reservation.

Reykjavik, Capital Region

An oceanfront thermal bath in Kópavogur near Reykjavik, open daily with outdoor pools facing the sea and walk-in day passes.

Tyrol, Bavaria

Hotel spa in Kreuth-Reitrain near Tegernsee with a 3,000 sqm onsen-style bathing area, hot and cold pools, saltwater pools and sauna, open on a day-pass basis.

Ourense, Galicia

An outdoor hot-springs spa in Ourense with thermal pools, walk-in day passes, and hours that run late on weekends.

Bath, England

A small open-air thermal pool in a separate building from Thermae Bath Spa's main complex, with its own changing rooms and day-pass access.

Lake Tahoe, California

Hotel-only spa at a lakefront resort in South Lake Tahoe, with an outdoor heated pool, Jacuzzi and treatment rooms aimed at couples.

Miami, Florida

A large hotel wellness resort on North Beach with a European-style hydrotherapy circuit, cryotherapy, acupuncture and an oceanfront fitness center.

Napa Valley, California

Adults-only resort spa in Napa Valley with pools, sauna, steam and a fitness center, open to hotel guests and club members via day pass.

Pagosa Springs, Colorado

Day-pass hot springs resort in Pagosa Springs with over 50 mineral pools fed by the Mother Spring, plus a spa for massages and body treatments.