Spas with reservation required

Philadelphia, Pennsylvania

Hotel spa on the third floor of The Rittenhouse overlooking Rittenhouse Square, with massage, facials, body treatments and a salon.

Elkridge, Maryland

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.

Orlando, Florida

Hotel spa at the Rosen Centre on International Drive in Orlando, offering massages, facials, nail care and access to a steam room, pool and fitness center.

Palm Springs, California

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

Sonoma, California

Hotel spa at The Lodge at Sonoma with an outdoor terrace, soaking pool, plunge pool and barrel sauna, open daily 9am-5pm, adults-only, reservation required.

Springboro, Ohio

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

Portland, Oregon

Adults-only day spa in Portland's Hosford-Abernethy neighborhood offering facial treatments by appointment in private suites, no walk-ins or day passes.

Coorg, Karnataka

Riverside resort spa in Coorg with private bungalows, a pool, and spa treatments along the Kaveri River; booking required.

Rishikesh, Uttarakhand

An upscale riverside resort 18 km outside Rishikesh with an in-house spa, yoga studio and restaurant, open only to overnight guests by reservation.

Naples, Florida

Sole-practitioner day spa in Naples, FL offering massage, cupping, facials and a plumbed Japanese-style head spa, with private treatment suites.

South Jordan, Utah

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

Ubud, Bali

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

Mérida, Yucatán

Resort spa on the grounds of Hacienda Xcanatun near Mérida, with a pavilion over a pond offering Asian-style massages and facials by reservation.

Miami, Florida

A beer-bath spa in Little Haiti where you soak in a cedar tub infused with hop ingredients and sip a cold beer on tap.

Scottsdale, Arizona

Hammam-inspired hotel spa at Omni Scottsdale Resort & Spa at Montelucia in Paradise Valley, with private suites and massage, facial and body treatments for

Baños, Tungurahua

Day spa in Baños with 46 treatments, 11 themed rooms, and skincare made from garden-grown herbs, fruit and volcanic ash.

Sonoma, California

A moderate-priced day spa a block off Sonoma Plaza offering massage and facials from a certified therapist and licensed esthetician, with private treatment

San Diego, California

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

Miami, Florida

A Brickell medical spa running 18 categories of non-invasive aesthetic treatments, including Botox, fillers and a signature facial, weekdays only.

Portland, Oregon

Day spa and natural medicine clinic in NW Portland's Slabtown with sauna, hydrotherapy, massage, acupuncture and a vegan café on site.

Santa Barbara, California

A State Street halotherapy spa built around a large underground crystal salt cave, with massage, facials and a relaxation lounge.

Kandy, Central Province

An adults-only Ayurvedic retreat in the hills above Kandy, Sri Lanka, with overnight stays, yoga and a restaurant, but no day-pass access.

Punta Cana, La Altagracia

Upscale day spa in Punta Cana offering massages, facials, a thermal pool and ocean-view relaxation lounges, open daily 9am-7pm.

Transylvania County, North Carolina

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