Spas with hotel guests only

Miami, Florida

Hotel spa at The Ritz-Carlton Key Biscayne, Miami, with treatment suites, sauna, steam room and whirlpool, open to hotel guests 18 and up by appointment.

Galway, Connacht

Adults-only hotel spa in Galway with a thermal suite, hydro pool and sauna; day pass runs about €50 and reservations are required.

Chicago, Illinois

A hotel spa on Trump Chicago's mezzanine level offering day passes, 22 treatments, a heated pool, steam room, sauna and fitness club; minimum age 16.

Pagosa Springs, Colorado

Hot springs resort in Pagosa Springs, Colorado, built around the geothermal Mother Spring, open daily for day-pass soaking or overnight stays.

Hua Hin, Prachuap Khiri Khan

Hotel spa at The Standard, Hua Hin, offering 11 treatments, ice bath therapy, and a day pass option at a beachfront resort on Naresdamri Road.

Miami, Florida

Adults-only hotel spa on Belle Isle near South Beach with a hammam, sauna, ice room, infinity pool and a day pass option for non-guests.

Philadelphia, Pennsylvania

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

Boston, Massachusetts

Hotel spa inside the Four Seasons One Dalton in Back Bay, with six treatments, a couples' suite and a 64-foot lap pool, open to hotel guests.

Dax, Nouvelle-Aquitaine

Family-run thermal hotel in Dax with a supervised pool, sauna, hammam and a 20-treatment mini-cure over five days, plus day-pass access to the spa.

San Pedro de Atacama, Antofagasta

A hotel spa inside the luxury Tierra Atacama lodge near San Pedro de Atacama, with indoor and infinity pools, sauna, steam room and treatment rooms, open only

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

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.

Auckland

A family-run rainforest resort in the Waitakere Ranges near Auckland offering a day spa, private yoga and free hiking and biking trails.

Orlando, Florida

A hotel spa at Waldorf Astoria Orlando offering massages, facials and a Himalayan salt room, open daily 9am-5pm with day passes available.

Bled, Upper Carniola

Hotel spa at Bled's Rikli Balance Hotel with six pools, six saunas and lake views, open to hotel guests only.

Yalova

Historic Ottoman-era thermal baths in Yalova's Termal district, with day-pass access to pools and private bath cabins.

Orlando, Florida

Adults-only hotel spa at the Hilton Orlando with a sauna, steam room, cold plunge and thermal pools, plus couples treatments and HydraFacials.

Miami, Florida

Hotel spa inside the InterContinental Miami, open daily with a day pass option, 11 treatments and a signature Raindrop Massage.

Tel Aviv, Tel Aviv District

Hotel spa inside Hotel Drisco Tel Aviv on Ben Yehuda Street, with rooftop baths, a Jacuzzi and couples' treatment rooms.

Vals, Grisons

Peter Zumthor's quartzite thermal baths in Vals, built into the mountain, open to day visitors as well as hotel guests.

Bridgetown, Christ Church

Hotel spa at Accra Beach Hotel in Christ Church, Barbados, with six treatment rooms, a sauna and steam room, open daily 8am-7pm for hotel guests.

Amalfi Coast, Campania

Hotel spa inside a former 13th-century monastery in Amalfi, with hammam, couple rooms and sauna, open to guests only.

Hunter Valley, New South Wales

A resort spa inside Avani Cypress Lakes in Pokolbin, open to hotel guests for treatments, thermal pools, outdoor baths and a fitness and yoga space.