Spas with private suites

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.

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.

Durango, Colorado

A hot springs resort in the Animas Valley near Durango, Colorado, with 32 mineral pools, cold plunges, a lap pool and private cedar soaking tubs.

Tuscany

Hotel spa inside Florence's Four Seasons, with a walled garden pool, whirlpool, sauna, steam room and couples suite, open to day-pass guests.

Nashville, Tennessee

A Finnish-inspired bathhouse and salon in a converted East Nashville factory, with sauna, steam room, cold plunge and private suites for couples.

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.

Shibu Onsen, Nagano

Reservation-only private hot spring and sauna suites at a Nagano brewery complex, built around a craft beer bathing plan for two to four guests.

Philadelphia, Pennsylvania

A Russian-Turkish bathhouse in Southampton, outside Philadelphia, with platza massage, a pool and multiple heat rooms, open to walk-ins with day passes.

Austin, Texas

Adults-only hotel spa at the Fairmont Austin with nine treatment rooms, a hydrotherapy circuit, sauna and cold plunge, open daily with day passes available.

Carmel-by-the-Sea, California

Resort spa at Carmel Valley Ranch with 12 treatment rooms, private terraces, a saltwater pool and infinity hot tub, open to adults by reservation.

San Diego, California

Adults-only day spa at Mission Bay Resort with massage, facials, Himalayan salt treatments and couples suites; walk-ins and day passes welcome.

Palm Springs, California

Hotel spa at the Renaissance Esmeralda in Indian Wells offering desert-inspired treatments, a recovery lounge, steam rooms and day passes, adults only.

San Diego, California

Adults-only hotel spa at Kona Kai Resort on Shelter Island with six treatment rooms, a couples' suite and day-pass access for non-guests.

Nashville, Tennessee

A Germantown contrast therapy studio with private suites pairing infrared sauna, cold plunge and a vitamin-c shower; day pass is $70.

Charleston, South Carolina

Contrast therapy studio in Mt Pleasant offering private 60-minute sessions with infrared sauna, cold plunge and vitamin-c shower; day pass $60.

Palm Beach, Florida

A Palm Beach Gardens studio offering 60-minute private-suite sessions combining infrared sauna, cold plunge and vitamin-c shower.

Charleston, South Carolina

Private contrast-therapy suites with infrared sauna, cold plunge and vitamin C shower in West Ashley, Charleston, by reservation.

London, England

A Russian-style banya bathhouse in Belgravia offering oak-lined steam rooms, cold plunge pools and leaf-massage rituals, with day passes by reservation only.

Lake Tahoe, California

A 17-room, adults-only hotel spa at Lake Tahoe's Ritz-Carlton with a heated lap pool, sauna and steam room; day pass access requires booking a treatment.

Portland, Oregon

Adults-only hotel spa in downtown Portland with a $50 day pass, infinity pool, sauna, steam room and cold plunge shower, booked in advance only.

Scottsdale, Arizona

Resort spa at Camelback Inn in Scottsdale with 20 treatment rooms, a thermal circuit and day-pass access open to non-guests.

Napa Valley, California

Adults-only hotel spa in Napa Valley with a co-ed thermal circuit of sauna, steam room and cold shower, open daily 10am–6pm; day passes available.

Milan, Lombardy

A luxury hotel spa inside Four Seasons Hotel Milano with a 14-metre pool under a vaulted ceiling, sauna, gym and private suites for couples' treatments.

Taipei

Hotel spa in Taipei's Songshan district with private suites, sauna, steam room and a heated outdoor pool, open daily with day passes for non-guests.