Spas with overnight stay

Wulai, New Taipei

A hilltop Wulai B&B with sodium bicarbonate hot-spring baths in every room and an outdoor infinity pool, geared toward couples.

Berkshires, Massachusetts

A nine-room boutique inn in Lee, Massachusetts, where overnight guests can book in-room massages and couples treatments rather than drop-in spa day passes.

Calistoga, California

A 1952 Calistoga hot springs resort with three mineral pools at 85, 95 and 104°F, mud baths, overnight rooms and a day-pass option.

Ginzan Onsen, Yamagata

A riverside hotel spa in Ginzan Onsen with a thermal bathing pool, overnight stay and day-pass access for non-guests.

Koh Samui, Surat Thani

Kamalaya Koh Samui is an adults-only destination spa and wellness retreat on Laem-Set Rd with over 100 treatments, thermal circuits and multi-day health

Thatcher, Idaho

A riverside hot springs in Thatcher, Idaho, with outdoor thermal pools, day passes, and overnight stays in yurts, cabins, or tents.

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.

Palm Springs, California

Boutique hotel spa in Desert Hot Springs with two natural mineral hot spring pools, day passes, and overnight rooms that include breakfast.

Seattle, Washington

A themed-suite day spa in Seattle's SODO district offering massages, facials, couples packages and a few overnight suites.

Hévíz, Zala

A natural thermal lake and medical spa in Hévíz, Hungary, offering mud and weight baths, massage and physiotherapy, open daily 9:00–18:30.

Bagno Vignoni, Tuscany

A 5-star hotel spa resort in Bagno Vignoni with thermal pools, open only to overnight guests staying in the Val d'Orcia countryside.

Coorg, Karnataka

Riverside resort spa in Coorg with private bungalows, a pool, and spa treatments along the Kaveri River; booking required.

Phoenix, Arizona

An all-suite Phoenix resort where the spa menu comes bundled with a 7-acre water park, but access is limited to hotel guests.

Băile Herculane, Caraș-Severin

Hotel-based thermal spa in Băile Herculane with sulfur mineral baths, indoor and outdoor pools, jacuzzi and sauna, open to hotel guests.

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.

Băile Herculane, Caraș-Severin

A 4-star hotel in central Băile Herculane with thermal pools, saunas, balneo and physiotherapy treatments, open to overnight guests.

Leukerbad, Valais

A 30-room hotel in Leukerbad with a private thermal pool and sauna chalet, open to overnight guests only, overlooking the Gemmi massif.

Soufrière

Resort spa at Ladera in Soufrière, St Lucia, set between the Pitons with day-pass access to pools, outdoor baths and treatments for couples.

Tucson, Arizona

Lakeside Spa at this 398-room desert resort in Tucson is open to hotel guests only, with two heated pools, a Jacuzzi and mountain views of Catalina range.

Kurokawa Onsen, Kumamoto

Okunoyu is a ryokan onsen in Kurokawa Onsen, Kumamoto, with outdoor thermal baths open to day visitors and overnight guests, daily 8:30am–8:30pm.

Bad Ischl, Upper Austria

A salt-and-brine thermal bath complex in Bad Ischl with indoor/outdoor pools, a sauna world, and a rooftop wellness deck at the attached hotel.

Fort Lauderdale, Florida

Hotel spa at The Atlantic Resort on Fort Lauderdale Beach with sauna, steam room, cold plunge and thermal pool, for overnight guests only.

Coorg, Karnataka

A luxury coffee-plantation resort in Coorg with a spa and pool facilities reserved for overnight guests.

Baden bei Wien, Lower Austria

A thermal bath in Bad Vöslau with four mineral-water pools fed by the original Vöslauer spring, plus sauna and steam room.