Spas with relaxation lounge

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.

Amsterdam, North Holland

A day spa inside a former bank vault in central Amsterdam, with pool, whirlpool and a canal-view gym; adults-only, day pass by reservation.

Barcelona, Catalonia

Adults-only thermal baths in a converted 18th-century building near Barcelona's Born market, with soaking pools, massages and couples rituals.

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.

Amman

A hotel hammam in Tla al-Ali, Amman, with marble bathing halls, a hot pool, sauna and Jacuzzi, offering about 20 treatments from a basic scrub to a $120

Bad Gastein, Salzburg

Thermal baths in Bad Hofgastein with indoor/outdoor pools, bathing lakes, slides, saunas and a sports medicine center, open daily year-round.

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.

Daylesford, Victoria

A rammed-earth house on 80 hectares near Daylesford, rented whole for up to 10 adults, with in-room massage and a two-night minimum stay.

Aspen, Colorado

A reservation-only Aspen studio offering private sound, energy and subconscious-journey sessions instead of classic spa treatments.

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.

Washington, D.C., District of Columbia

A multi-level day spa near DC with indoor and rooftop hydrotherapy pools, several sauna types, lounges, an a la carte spa menu and eateries.

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.

Austin, Texas

Medical spa and day spa on South Lamar offering facials, injectables, massage and a signature $1,499 Mermaid Lift, open daily with private rooms and a stocked

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.

Portland, Oregon

Neighborhood day spa in Portland's Overlook area with a private soak-and-steam retreat studio, massage, skincare and nail services.

Baden-Baden, Baden-Württemberg

Modern thermal baths in Baden-Baden with indoor-outdoor pools and a Roman-style sauna garden, open daily 8am–10pm, day pass €40.

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.

San Francisco, California

A hotel spa at Fort Baker near Sausalito for Cavallo Point guests, with a meditation pool, Zen garden, infrared sauna and outdoor Jacuzzis.

Hot Springs, Arkansas

A combined day spa and med spa in Hot Springs offering massages, facials, laser treatments and lunch-inclusive packages by reservation.

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.

Washington, D.C., District of Columbia

24/7 men's bathhouse in Logan Circle with sauna, steam room, lounge, and private rooms, clothing optional, 18+ with ID.

Chicago, Illinois

Walk-in reflexology and massage spa in the Chicago Loop with foot soaks, hot stone work and a $59 combo massage.

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.