Spas with reservation required

Idaho City, Idaho

A reservation-only hot springs soak in Idaho City with private tubs, a steam room and a $30 day pass, open five days a week.

Miami, Florida

Hotel spa inside Trump National Doral with 42 treatments, couples massages, sauna, steam room, cold plunge and jacuzzi, open daily 9am-7pm.

Philadelphia, Pennsylvania

Hotel spa in Center City Philadelphia with a heated indoor saltwater pool, fitness center and day-pass access for non-guests.

Aspen, Colorado

Adults-only hotel spa at Viewline Resort Snowmass with a $25 day pass, steam rooms, outdoor pool and whirlpool, reservations required.

Sedona, Arizona

Adults-only resort spa in Sedona with outdoor hot tubs, steam rooms and a 30-treatment menu, open daily with walk-ins and day passes.

Washington, D.C., District of Columbia

Hotel spa inside the Willard InterContinental in downtown D.C., with sauna, steam room and massage and facial treatments, by reservation only.

Canggu, Bali

A hotel spa at Theanna Villa in Canggu with a pool, gym, restaurant and shuttle service, open to guests by reservation only.

Aix-les-Bains, Auvergne-Rhône-Alpes

Medical thermal baths in Aix-les-Bains treating respiratory and oral mucosal conditions with sulfur-rich water, mostly through prescribed multi-day cures.

Cedar Park, Texas

Cedar Park float spa offering sensory-deprivation float therapy plus sauna, steam room and cold plunge, open daily 8am-10pm.

Palm Springs, California

A 16-room adults-only hotel in Desert Hot Springs with three natural mineral-water pools fed by a 350-foot geothermal well, plus a small on-site spa and

Key West, Florida

A medical spa in Key West offering Morpheus8, injectables and body contouring, with a sauna, steam room and thermal pool on site by appointment only.

Merano, Trentino-South Tyrol

An adults-only, guests-only longevity retreat and hotel spa in Merano with a medical-led wellness institute and private suite treatments.

Rogaška Slatina, Savinjska

Wellness center at Grand Hotel Rogaška in Rogaška Slatina, Slovenia, with pools, saunas and fitness; day pass available by reservation.

Miami, Florida

Hotel spa at The Setai in Miami Beach with 7 ocean-view treatment rooms, 5 couples suites, saunas, steam and a cold plunge.

Chicago, Illinois

A Near South Side day spa pairing Chinese-technique massage and foot reflexology with a wine and cocktail menu, priced for couples visits.

Gold Coast, Queensland

A 90-minute hydrotherapy circuit in Southport with a Finnish rock sauna, 5° ice baths and hot/cold magnesium pools, day pass $49.

Scottsdale, Arizona

Adults-only hotel spa at the Fairmont Scottsdale Princess with a rooftop pool, grotto waterfall pool, sauna, steam room and cold plunge, open daily 6am-7pm.

Dubai

Hotel spa inside Fairmont Dubai on Sheikh Zayed Road, offering massage, hammam and couples treatments by reservation only, no day pass.

Houston, Texas

A Houston day spa on E Airtex Dr with two locations, offering massage, facials and body treatments alongside a sauna, steam room, cold plunge and thermal pool.

Carmel, Indiana

A moderate-priced day spa in Carmel, Indiana with sauna, steam room and thermal pool, plus facials, massage and body contouring treatments.

Santa Fe, New Mexico

A 16,000-square-foot adults-only hotel spa at Hilton Buffalo Thunder near Santa Fe, with separate men's and women's saunas, steam rooms and whirlpools.

Nashville, Tennessee

Upscale day spa in Franklin outside Nashville offering facials, massages, a salt room, infrared sauna and hydrotherapy tub, open daily by reservation.

Houston, Texas

Luxury day spa near Houston's Galleria with massage, facial and body treatments, a salt room and infrared sauna; reservations only, no walk-ins.

Charleston, South Carolina

A 52-treatment luxury day spa in Mount Pleasant near Charleston, with Vichy showers, couples suites and a $370 signature package; reservations required.