Spas with reservation required

Seattle, Washington

A private floating bathhouse on Seattle's Lake Union, booked out entirely for one group of up to 12 for sauna, cold plunge and hot tub rounds.

Miami, Florida

Day spa in the Sherry Frontenac Hotel's lower lobby in Miami Beach, with sauna, steam, cold plunge and thermal pool alongside massage treatments.

Miami, Florida

A luxury day-pass wellness circuit inside Carillon Miami Wellness Resort, with sauna, steam, cold plunge and thermal pools in North Beach.

Plainfield, Indiana

Day spa in Plainfield, IN offering facials, massages and body-sculpting treatments alongside a sauna, steam room and thermal pool, reservation required.

Sacramento, California

Day spa in Sacramento's Oak Park with float rooms, private cold plunge and sauna suites, infrared sauna, and a Somadome meditation pod.

Medellín, Antioquia

Day spa in a rooftop wellness area at the Celestino Hotel in El Poblado, with sauna, steam room, jacuzzi, cold plunge and massage treatments.

Marrakech, Marrakesh-Safi

A 1,200-square-metre hotel spa at Selman Marrakech built around the Chenot method, with hammams, pools and multi-day wellness programmes.

Miami, Florida

Hotel spa inside Dua Miami, Autograph Collection in Brickell, open daily 9am-6pm, with sauna, steam room, cold plunge and couples massage rooms.

Austin, Texas

A North Austin head spa near The Domain built around Japanese-style scalp massage, with private, couples and group suites by appointment.

Hot Springs, Arkansas

Day spa and Aveda salon in Hot Springs with baths, a salt room, oxygen bar and massage, facial and hair services.

Charleston, South Carolina

A West Ashley day spa in Charleston offering lymphatic massage, infrared sauna, halo therapy and foot soaks by reservation, no day pass.

Denver, Colorado

Downtown Denver massage studio with 22 treatments, cold plunge and sauna, built for membership-based regular visits rather than one-off day passes.

Palm Springs, California

Hotel spa inside the Avalon in Palm Springs, open Thursday through Monday, with a $75 day pass covering jacuzzi, sauna, cold plunge and steam rooms.

Nashville, Tennessee

A Brentwood day spa focused entirely on scalp and head treatments, with private suites and a signature ritual built around halo water therapy.

New York City, New York

A below-street-level day spa in NoHo with thermal baths, a three-story indoor waterfall, sauna, steam room and cold plunge, plus massage and facial treatments.

Seattle, Washington

A Bellevue day spa in Wilburton specializing in head spa scalp treatments, massage, facials and couples sessions, with free on-site parking.

Atlanta, Georgia

A reservation-only wellness center in Edgewood, Atlanta offering colon hydrotherapy, hyperbaric oxygen therapy, sauna and an oxygen bar for couples or solo

Gold Coast, Queensland

An overnight wellness retreat in Tallebudgera Valley with a cedar sauna, magnesium spa bath, ice bath and a 60-minute aromatherapy massage.

Miami, Florida

A Peruvian-themed day spa inside the Victor Hotel on Ocean Drive, South Beach, with a hamam, steam room, sauna and a couples suite.

Portland, Oregon

A membership-driven wellness club in downtown Portland with hot pools, sauna, steam room and cold plunge, plus massage, skincare and fitness classes.

Miami, Florida

Nature-themed day spa in Brickell with hydro massage, a hydrotherapy circuit and couples treatments, open daily 9am-6pm.

Indianapolis, Indiana

Day spa in Allisonville, Indianapolis with sauna, steam room, thermal pool and cold plunge, plus about 10 massage and facial treatments for solo visits or

Austin, Texas

Hotel spa at Omni Barton Creek with steam room, sauna, cold plunge and a rooftop pool overlooking Hill Country, open daily 9am-7pm.

Miami, Florida

An upscale day spa on Miracle Mile in Coral Gables with sauna, steam room and cold plunge, known for a $200 signature treatment and couples packages.