Spas with moderate

Carson, Washington

A clothing-optional, adults-only mineral hot springs bathhouse in Carson, Washington, with a $12 day pass and a $30 bath-and-wrap treatment.

San Diego, California

Hotel spa at the Catamaran Resort in Pacific Beach, San Diego, with a bay-view hot tub, pool and restaurant, open to hotel guests only.

Many, Louisiana

Hotel spa at Cypress Bend Resort on Toledo Bend Lake in Many, Louisiana, with a sauna, hot tub, and heated indoor and outdoor pools.

San Diego, California

Hotel wellness facilities at the DoubleTree Del Mar in Carmel Valley, San Diego, with a sauna, steam room, outdoor pool and fitness center for hotel guests.

Mývatn, Northeastern Region

A 92-room hotel at Lake Mývatn with an in-house sauna for overnight guests only; no day-pass access.

Termas de Río Hondo, Santiago del Estero

An all-inclusive family resort in Termas de Río Hondo with thermal pools, a spa and buffet dining, open to hotel guests only.

Calistoga, California

A clothing-optional hot springs retreat outside Calistoga with eight mineral pools, spa bodywork, and day-pass, camping, and lodging options.

Los Baños, Laguna

A natural spring resort near Mount Makiling in Calauan, Laguna, with outdoor pools, forest trails, and day passes offered every day of the week.

North Royalton, Ohio

A North Royalton day spa built around a salt room and sauna, with adults-only halotherapy sessions on a walk-in or reserved basis.

Copenhagen, Capital Region

A Nørrebro day spa built around a salt room and sauna, open daily for walk-in visits, adults only.

Miami, Florida

A hotel spa in downtown Miami with a day pass covering sauna, steam, cold plunge and thermal pools, plus 13 treatments on the menu.

Las Vegas, Nevada

A Henderson day spa in MacDonald Ranch offering massage, facials and a Himalayan salt lounge, with walk-in and reservation options.

Palm Springs, California

A 10-room mineral hot springs hotel in Desert Hot Springs near Palm Springs, offering day passes to its 120°F spring-fed pools, sauna and massage rooms.

Karjalohja, Uusimaa

Lakeside resort spa on Lohjanjärvi in Karjalohja, about an hour from Helsinki, with a day pass, thermal pool, salt room and restaurant.

San Miguel de Allende, Guanajuato

A Saturday-only hot springs day spa near San Miguel de Allende with outdoor thermal pools and walk-in access.

Las Vegas, Nevada

Float tank, massage and salt therapy spot in Peccole Ranch, Las Vegas, open daily with walk-ins accepted alongside bookings.

Ojai, California

A small, independently owned day spa in Ojai offering facials, massage, head spa treatments, infrared sauna and salt therapy.

Santa Fe, New Mexico

A downtown Santa Fe day spa and oxygen bar offering massage, energy work and blessing ceremonies alongside an on-site apothecary restaurant and wellness shop.

San Francisco, California

An adults-only bathhouse in San Francisco's Tenderloin with a thermal pool and an on-site restaurant, open daily except Tuesdays.

Naples, Florida

Day spa in Central Naples with a salt cave for halotherapy, plus massage, facials and yoga classes; walk-ins welcome but reservations recommended.

Pamukkale, Denizli

A 315-room thermal resort in Karahayıt near Pamukkale with its own thermal pools, pine-shaded gardens and on-site dining, open to hotel guests only.

Palm Beach, Florida

Salt The Spa is a day spa in Wellington, near Palm Beach, built around a dedicated salt room and newer peptide-therapy treatments.

Reykjavik, Capital Region

An oceanfront thermal bath in Kópavogur near Reykjavik, open daily with outdoor pools facing the sea and walk-in day passes.

Lake Tahoe, California

A lakefront lodge in South Lake Tahoe where guest wellness amenities are a pool, hot tub and private beach rather than a treatment spa.