Spas with solo travelers

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.

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

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

A full-service salon and spa in Orlando pairing hair, skincare and waxing services with a monthly membership plan for mix-and-match treatments.

A hillside boutique hotel spa outside Sayulita with sauna, steam room, cold plunge and ocean-view pool, open on a day-pass basis.