Spas with thermal pool

A beachfront resort spa in North Beach, Miami with cryotherapy, a floating salt bath, sauna, steam and a cold plunge, open to walk-ins and day-pass guests.

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

A 24-hour Korean bathhouse in Duluth with a $30 day pass, sauna rooms, cold plunge, thermal circuits and a junior Olympic pool.

Adults-only spa inside the all-inclusive Ocean Riviera Paradise resort in Playa del Carmen, with sauna, Turkish bath and four treatment options via day pass.

A 38,000-square-foot resort spa at JW Marriott Desert Springs in Palm Desert offers day passes, saunas, a saltwater lap pool and couples suites.

Hotel spa and pool deck at a moderate-price resort in Osprey, Florida, with sauna, steam room and thermal circuits for overnight guests.

Hotel spa at The Atlantic Resort on Fort Lauderdale Beach with sauna, steam room, cold plunge and thermal pool, for overnight guests only.

A moderate-priced day spa in Charlotte's SouthPark area with a sauna, steam room and thermal pool alongside massage, facial and body-treatment menus.

Full-service resort spa at the Hyatt Regency Hill Country in San Antonio, with thermal circuits, cold plunge and day passes open to non-guests.

A resort spa inside the Iberostar Waves Tucán in Playacar offering sauna, Turkish bath and jet-pool treatments, open to day-pass visitors 16 and up.

An all-inclusive beachfront resort spa in Huatulco with a sauna, steam room and thermal pools, open only to hotel guests.

A hotel spa on Mission Bay in San Diego with sauna, steam room, cold plunge and thermal pools, open only to resort guests.