Spas with adults only

Toronto, Ontario

A reservation-only thermal bath circuit in a 1912 Edwardian building in Toronto, with eight pools, a dry sauna, steam room and massage treatments.

Barcelona, Catalonia

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

San Francisco, California

Adults-only Russian bathhouse in San Francisco's India Basin with steam rooms, cold plunge, rooftop deck and a café, open daily except Tuesday.

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.

Sydney, New South Wales

Korean bathhouse in Chatswood with herbal baths, steam room and dry sauna, built around the traditional Korean body scrub, open by reservation only.

Geneva

A central Geneva adults-only club built around a sauna, hammam and jacuzzi, with nightly themed events for swingers, couples and gay visitors since 1999.

Nashville, Tennessee

Upscale hotel spa inside 1 Hotel Nashville with 38 treatments, an infrared sauna wrap, and an 18-plus minimum age; no day pass offered.

San Diego, California

Thai massage studio in San Diego's Gaslamp Quarter offering massage, head spa, body scrub and infrared sauna, walk-ins welcome daily.

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.

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.

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.

Portland, Oregon

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

Austin, Texas

Contrast therapy studio in East Austin with a communal garden sauna-and-cold-plunge setup, private suites, and red light sessions, day passes from $25.

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

Hotel spa inside the Avalon in Palm Springs, open Thursday through Monday, with a $75 day pass covering jacuzzi, sauna, cold plunge and steam rooms.

Philadelphia, Pennsylvania

A reservation-only traditional Nordic sauna in North Philadelphia, open Wednesday through Monday and closed Tuesdays.

Houston, Texas

A Korean jjimjilbang in Houston with clothing-optional bathing pools, sauna and steam rooms, $58 day pass, adults 18+ only, walk-ins welcome.

New York City, New York

A below-street-level day spa in NoHo with thermal baths, a three-story indoor waterfall, sauna, steam room and cold plunge, plus massage and facial treatments.

Santa Fe, New Mexico

Santa Fe float spa with sensory-deprivation tanks and infrared sauna rooms, walk-ins accepted when the schedule allows.

Gold Coast, Queensland

An overnight wellness retreat in Tallebudgera Valley with a cedar sauna, magnesium spa bath, ice bath and a 60-minute aromatherapy massage.

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.

Miami, Florida

A co-ed Turkish hammam and day spa in North Miami offering a $125 day pass with saunas, steam rooms, a hydromassage pool and an on-site Turkish restaurant.

San Diego, California

A walk-in day spa in San Diego's Hillcrest neighborhood with massage, cryotherapy, salt therapy and a $100 all-day wellness pass.