Spas with reservation required

Carmel, Indiana

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

Milwaukee, Wisconsin

East Town Spa in Milwaukee's Juneau Town combines a full-service salon and med spa with a thermal circuit of sauna, steam, pools and cold plunge.

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.

Nashville, Tennessee

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

Key West, Florida

A day spa just off Duval Street in Key West offering massage, facials, waxing and a Vichy shower, with walk-ins possible but reservations preferred.

Tucson, Arizona

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

Colorado Springs, Colorado

An adults-only medical day spa in Colorado Springs offering constitutional hydrotherapy, infrared sauna and homeopathy by appointment.

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

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.

Richmond, Virginia

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

Santa Barbara, California

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

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

Minneapolis, Minnesota

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.

Charlotte, North Carolina

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.

San Diego, California

A budget-friendly massage and medspa in Core-Columbia, San Diego, with private suites, a sauna and a couples treatment room.

Orlando, Florida

Halotherapy day spa in Orlando's Lake Eola Heights offering salt room sessions, massage and acupuncture, adults only, by reservation.

Carmichael, California

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

Los Angeles, California

Walk-in-friendly day spa in Westlake, LA offering affordable massage and facial combos, with a sauna on site.

Palm Beach, Florida

An oceanfront resort spa in Riviera Beach combining Ayurvedic treatments with a hydrothermal circuit, hammam, salon and private beach access.

Santa Barbara, California

Adults-only day spa on State Street in Santa Barbara built around Jurlique skincare, with a sauna and reservation-only treatments at the luxury end of the

Encinitas, California

Adults-only day spa in Leucadia, Encinitas, about a mile from the beach, with private suites, a relaxation lounge and movement classes.