Spas with reservation required

A West Town day spa built around a beer soak, with sauna, steam room, salt room and thermal pool for couples or solo visits.

A themed-suite day spa in Seattle's SODO district offering massages, facials, couples packages and a few overnight suites.

A halotherapy day spa in West Elkridge, near Baltimore, built around a salt cave, massage rooms and a yoga studio, aimed at solo adult visitors.

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

A wellness center in Springboro, Ohio built around a natural salt cave, with energy healing, sound baths and metaphysical classes for individuals or groups.

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.

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

All-inclusive multi-night wellness retreat in Pisgah Forest, NC, combining fitness classes, spa treatments, guided hikes and farm-to-table meals in private

A single-room salt cave in a Carmichael strip mall offering 45-minute salt therapy sessions for relaxation and respiratory relief.

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

Float tank, massage and salt therapy spot in Peccole Ranch, Las Vegas, open daily with walk-ins accepted alongside bookings.