Spas with thermal pool

Florence, Tuscany

A 650-square-meter spa inside a 14th-century Florence monastery, with thermal pool, guesthouse rooms, bistro and day-pass access.

Durango, Colorado

A hot springs resort in the Animas Valley near Durango, Colorado, with 32 mineral pools, cold plunges, a lap pool and private cedar soaking tubs.

Jūrmala

A pool-and-sauna complex inside Pegasa Pils Hotel in Jūrmala, with a 12.5m pool, three saunas, steam room and a salt room; day passes available, minimum age 16.

Mývatn, Northeastern Region

A geothermal lagoon by Lake Mývatn in North Iceland, with hot tub, steam cave, swim-up bar and massages, open daily noon to 10pm.

Palm Beach, Florida

A 42,000-square-foot hotel day spa in Manalapan with a central dipping pool, garden lounge areas, and day passes open to non-guests.

Palm Springs, California

Moroccan-themed inn in Desert Hot Springs with natural mineral hot springs, a spring-fed pool and day-pass access from 9am to 4pm.

Vail, Colorado

Adults-only day spa at The Charter at Beaver Creek with saltwater pools, steam room, sauna and a day pass for treatments or facility access.

Noosa, Queensland

Day spa on Hastings Street in Noosa Heads with a hydrothermal circuit, day passes, and walk-ins welcome.

Scottsdale, Arizona

Day spa in South Scottsdale focused on facials and a signature holistic massage, with sauna, steam room, thermal pool and cold plunge on site.

Monroe, New Jersey

Affordable day spa in Williamstown, NJ with sauna, steam room and thermal pool, offering massages, facials and couples treatments.

Columbia, Maryland

A luxury medical and day spa in Columbia's Town Center combining facials, massage and laser/injectable treatments with a thermal pool, sauna and steam room.

Montego Bay, Saint James

A 12-treatment hotel spa at Half Moon resort in Montego Bay, with a waterfall-fed lagoon pool, steam rooms and outdoor yoga, open to resort guests only.

Tuscany

Hotel spa inside Florence's Four Seasons, with a walled garden pool, whirlpool, sauna, steam room and couples suite, open to day-pass guests.

Baden-Baden, Baden-Württemberg

A Renaissance-era thermal bathhouse in Baden-Baden built in 1877, offering a structured Roman-Irish bathing ritual for about 39 euros a day.

Houston, Texas

A Korean jjimjilbang in Houston with clothing-optional bathing pools, sauna and steam rooms, $58 day pass, adults 18+ only, walk-ins welcome.

Orlando, Florida

Medical spa in Orlando offering facials, massage, body contouring and couples packages, with an on-site sauna, steam room and thermal pool.

Temescal Valley, California

Adults-only hot springs resort in Temescal Valley with 19 outdoor mineral pools, red clay baths, and a cave-like grotto, open daily 9:30am-5pm.

Calistoga, California

A Calistoga hot springs spa built around mud baths, with private couples rooms and mineral pools open daily from 8am to 11pm.

New York City, New York

A below-street-level day spa in NoHo with thermal baths, a three-story indoor waterfall, sauna, steam room and cold plunge, plus massage and facial treatments.

The Hamptons, New York

Oceanfront resort spa in Montauk with a seawater and marine-based treatment menu, hydrotherapy, contrast bathing, and a heated saltwater pool.

Hajdúszoboszló, Hajdú-Bihar

A medical thermal bath in Hajdúszoboszló, Hungary, with iodine-bromine-salt water pools treating rheumatic and joint conditions, open daily 7am–7pm.

Madrid, Community of Madrid

A Moorish-style hammam near Plaza Mayor in central Madrid, with thermal pools, a relaxation lounge and treatment packages for adults and couples.

Hanmer Springs, Canterbury

New Zealand's largest geothermal hot pool complex in Hanmer Springs, with pools from 28°C to 42°C, a lazy river, slides and alpine views.

Tucson, Arizona

A resort spa in Tucson's Starr Pass area with a saline lap pool, sauna and fitness center, plus signature treatments from $159 for hotel guests.