Spas with reservation required

Catskills, New York

A small storefront in Catskill, NY offering whole-body cryotherapy, infrared sauna and red light therapy sessions, open most days except Tuesday and Wednesday.

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.

São Paulo

A holistic wellness center in São Paulo's Paraíso district running ayahuasca ceremonies, tarot sessions, massage therapy and weekend forest retreats with cabin

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.

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.

Hudson Valley, New York

Day spa near Wallkill and Gardiner in the Hudson Valley offering massage, skincare and energy-healing treatments, with an on-site bed and breakfast for

Vail, Colorado

A Vail day spa offering customized massages and facials plus a recovery room with infrared sauna, cold plunge and yoga mats.

Portland, Oregon

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

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

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.

Barcelona, Catalonia

Rooftop day spa at Casa Bonay hotel in Eixample with dry sauna, hammam, ice bath and a Japanese ofuro, booked by small-group circuit or free use.

Vichy, Auvergne-Rhône-Alpes

Adults-only thermal baths in Vichy using the town's mineral spring water, with a hydrotherapy circuit and thermal pool, booking required.

Tucson, Arizona

Day spa near Swan Way Park in Tucson with a cedar hot tub, cold plunge, infrared sauna and massage, bookable by reservation for adults only.

Solvang, California

A resort spa inside Alisal Ranch, a 10,500-acre luxury guest ranch in Santa Ynez Valley open only to overnight guests by reservation.

Palm Beach, Florida

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

Hudson Valley, New York

Hotel spa at a small Hudson Valley inn on 75 riverside acres in Milton, NY, open to overnight guests by reservation while the spa undergoes renewal.

Berkshires, Massachusetts

An all-inclusive destination resort in the Berkshires combining spa treatments, fitness, and themed wellness retreats, open daily with reservations required.

Manuel Antonio, Puntarenas

A destination spa with outdoor thermal pools near Manuel Antonio, Costa Rica, open daily with reservations required.