Spas with thermal pool

Spa, Liège

Thermal baths in the town of Spa, Belgium, fed by natural mineral water, with saunas, hammams and separate textile and naturist relaxation areas.

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

Rogaška Slatina, Savinjska

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

Rotorua, Bay of Plenty

A Rotorua day spa built around Ngāti Whakaue hot-springs traditions, centered on a seven-step geothermal Restorative Journey with lakeview thermal pools, mud

Carmel, Indiana

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

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.

Mornington Peninsula, Victoria

Adults-only bathhouse in Mornington with magnesium baths, ice plunge, sauna and steam rooms; walk-ins welcome.

Austin, Texas

Day spa in Steiner Ranch, Austin, offering sauna, steam room, thermal pools, cold plunge and a signature scalp treatment for adults, open Monday through

Brežice, Posavje

A large thermal water park in Brežice, Slovenia, with a year-round indoor pool riviera, an adults-only sauna zone, and seasonal outdoor slides.

Berlin

A saltwater thermal pool under a concrete dome near Berlin's Tempelhofer Feld, with sauna, steam room and occasional DJ nights.

Tulum, Quintana Roo

Members-only contrast-therapy spa in La Veleta, Tulum, with a dry sauna, cold plunge, hot tub and a quiet pool for adults only.

Puelo, Los Lagos

Adults-only hot springs in Puelo with ten thermal pools, a sauna, steam room and individual herbal tubs, open daily with walk-in day passes.

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.

Milan, Lombardy

Adults-only day spa in a Liberty-style building near Milan's Parco Sempione, with thermal pools, saunas, steam room and a hydrotherapy circuit.

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.

Vals, Grisons

Peter Zumthor's quartzite thermal baths in Vals, fed by a 30°C mineral spring, open to day visitors as well as hotel guests.

Portland, Oregon

Adults-only hotel and thermal springs on NE Alberta St in Portland, with vitality pools, a day-pass option, and spa treatments.

Carson, Washington

A clothing-optional, adults-only mineral hot springs bathhouse in Carson, Washington, with a $12 day pass and a $30 bath-and-wrap treatment.

Jerusalem, Jerusalem District

An adults-only resort spa in the Judean Hills outside Jerusalem, with indoor and outdoor pools, a hammam and a day-pass option.

Granada, Andalusia

An Arab-style bathhouse in Granada's Centro district with thermal pools and a relaxation lounge, open daily 10am–10:30pm, adults only.

San Diego, California

Adults-only hotel spa in Carmel Valley with sauna, steam, cold plunge and thermal circuits, open to guests of the Fairmont Grand Del Mar.

Vancouver, British Columbia

A hotel spa inside Fairmont Pacific Rim in downtown Vancouver, with sauna, steam, pools, cold plunge and thermal circuits, open to hotel guests only.

Scottsdale, Arizona

Adults-only resort spa in Scottsdale with sauna, steam, cold plunge and thermal pools, open only to hotel guests.

San Diego, California

A 21-and-over hotel spa in San Diego's Gaslamp Quarter with sauna, steam room, cold plunge and thermal pools, open to hotel guests only.