Spas with thermal pool

Las Vegas, Nevada

Adults-only hotel spa inside ARIA Resort & Casino in Las Vegas, with sauna, steam room, thermal pools and cold plunge, open to hotel guests 18 and up.

Bagno Vignoni, Tuscany

Hotel spa in a 15th-century Bagno Vignoni palazzo with a thermal pool fed by the village's natural hot springs, open to day visitors.

Längenfeld, Tyrol

A large thermal bath and 4-star hotel spa in the Ötztal valley near Längenfeld, with indoor-outdoor pools, a sauna garden and a dedicated kids' water world.

Palm Springs, California

Adults-only hot springs resort on Miracle Hill in Desert Hot Springs with private mineral tubs, a Finnish sauna, salt room and 35 spa treatments.

Tenerife, Canary Islands

A hotel spa at Bahía del Duque in Costa Adeje with an outdoor seawater thalassotherapy circuit, hammam, saunas and a cold plunge, open to day visitors.

O Grove, Galicia

A thermal spa on Isla de la Toja combining a seawater hydrotherapy circuit with a mineral-medicinal water balneario, open daily with a day pass option.

Doha

Hotel spa inside Banyan Tree Doha with separate men's and women's hydrothermal suites, open daily 10am-11pm to hotel guests only.

Calistoga, California

A moderate-priced resort spa in Calistoga with geothermal mineral pools, open daily 9am-5pm and offering day passes to the public.

Miami, Florida

A beachfront resort spa in North Beach, Miami with cryotherapy, a floating salt bath, sauna, steam and a cold plunge, open to walk-ins and day-pass guests.

Karlovy Vary, Karlovy Vary Region

A 5-star medical spa and wellness hotel beside Karlovy Vary's colonnades, with seven saunas, five pools and a day pass for non-guests.

Riviera Maya, Quintana Roo

Adults-only hotel spa at Devossion by Live Aqua in Playa del Carmen, open daily 8am-8pm, with sauna, steam room and pools for resort guests.

Marrakech, Marrakesh-Safi

A 1,200-square-metre hotel spa at Selman Marrakech built around the Chenot method, with hammams, pools and multi-day wellness programmes.

Chicago, Illinois

Adults-only hotel spa in River North with a 67-foot pool, multiple sauna and steam rooms, and day passes for non-guests.

Stockholm, Stockholm County

A hotel spa on Södermalm with indoor and outdoor pools, a dry sauna and a steam room, open to day-pass visitors aged 16 and up.

Portland, Oregon

A member-run bathhouse in Concordia with a clothing-optional salt-water hot pool, cedar sauna and courtyard, day passes from $18.

Miami, Florida

Hotel spa inside Dua Miami, Autograph Collection in Brickell, open daily 9am-6pm, with sauna, steam room, cold plunge and couples massage rooms.

Palm Springs, California

Moroccan-themed inn in Desert Hot Springs with natural mineral hot springs, a spring-fed pool and day-pass access from 9am to 4pm.

Mallorca, Balearic Islands

A clifftop luxury hotel spa near Cas Català-Illetes with an infinity pool, relaxation pool and a seasonal Spa Bodyna, open to day visitors as well as guests.

Opatija, Primorje-Gorski Kotar

A 5-star hotel spa in Opatija with a sauna centre, seawater pools and couples treatments, open only to Hotel Ambasador guests.

Krynica-Zdrój, Lesser Poland

Mountain resort spa in Krynica-Zdrój with indoor and outdoor pools, a sauna complex, and a clothing-optional 18+ zone; day passes available.

Velingrad, Pazardzhik

Hotel spa in Velingrad with mineral-water pools, saunas, steam rooms and a hammam spread over 4,000 square metres; day passes are available.

Archena, Murcia

A 19th-century thermal hotel in Archena with direct access to a Roman-era spring complex, open to day visitors as well as overnight guests.

Bük, Vas

Hotel spa in Bükfürdő with pool, jacuzzi, saunas and massage services, open to guests staying in either of its two linked wings.

Bursa

A historic thermal bathhouse and small hotel in Bursa's Kükürtlü district, with separate men's and women's hamams, day passes, and overnight stays.