Spas with reservation required

Day spa in West Sedona with sauna, steam room and a thermal pool, open daily by reservation and set up for couples treatments.

Downtown Palm Springs day spa built around a natural hot mineral spring, with private mineral baths, sauna, steam room and massage.

A no-frills contrast therapy studio in Carmel, Indiana, built around a 30-minute sauna-and-cold-plunge circuit for solo visitors.

A day spa and wellness center in South Jordan, Utah, with a salt room, infrared sauna, cold plunge, float therapy and a yoga studio.

An adults-only wellness retreat on Ubud's Ayung River offering multi-day healing programmes, thermal circuits and plant-based cuisine by reservation only.

Float Horizen is a day spa in Nashville's East End offering sensory-deprivation float tanks, infrared sauna, massage and sound meditation sessions.

Day spa in Tucson's La Encantada shopping center with a thermal circuit of sauna, steam room, cold plunge and soaking pools.

A Clairemont wellness studio in San Diego pairing acupuncture and bodywork with an infrared sauna and a Himalayan salt room for classes.

Day spa in Richmond's West End with massage, organic facials, HydraFacial, infrared sauna and herbal bath soaks; walk-ins welcome, reservations recommended.

A moderate-priced day spa in Minnetonka with a sauna, steam room, thermal pool and cold plunge, set up for couples and adults-only visits.

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.

A North Royalton day spa built around a salt room and sauna, with adults-only halotherapy sessions on a walk-in or reserved basis.

A Northeast Minneapolis wellness studio rooted in Traditional Chinese Medicine, offering sauna access by reservation in the Bottineau neighborhood.

A medical spa in central Scottsdale offering 32 treatments—facials, massage, Botox, and a bridal package—alongside a sauna, steam room and thermal pool.