Spas with walk-ins welcome

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.

Florence, Tuscany

A 650-square-meter spa inside a 14th-century Florence monastery, with thermal pool, guesthouse rooms, bistro and day-pass access.

Hot Springs, Arkansas

Day spa and Aveda salon in Hot Springs with baths, a salt room, oxygen bar and massage, facial and hair services.

Jūrmala

A pool-and-sauna complex inside Pegasa Pils Hotel in Jūrmala, with a 12.5m pool, three saunas, steam room and a salt room; day passes available, minimum age 16.

Mývatn, Northeastern Region

A geothermal lagoon by Lake Mývatn in North Iceland, with hot tub, steam cave, swim-up bar and massages, open daily noon to 10pm.

Charleston, South Carolina

A West Ashley day spa in Charleston offering lymphatic massage, infrared sauna, halo therapy and foot soaks by reservation, no day pass.

Denver, Colorado

Downtown Denver massage studio with 22 treatments, cold plunge and sauna, built for membership-based regular visits rather than one-off day passes.

Jackson Hole, Wyoming

A day spa next to the Trailborn hotel in Jackson Hole with an outdoor pool deck, salt lounge and day passes for walk-in soaks or treatments.

San Miguel de Allende, Guanajuato

Family-friendly hot springs park near San Miguel de Allende with indoor and outdoor thermal pools, a kids' splash area, and day passes for walk-ins.

Bad Füssing, Bavaria

Large thermal bath complex in Bad Füssing with 17 indoor and outdoor pools, a sauna area and therapy basins, open daily year-round.

Scottsdale, Arizona

Day spa in South Scottsdale focused on facials and a signature holistic massage, with sauna, steam room, thermal pool and cold plunge on site.

Houston, Texas

Day spa in Houston's Westside with a grotto pool, outdoor pool, steam rooms and sundeck, plus an on-site restaurant; walk-ins welcome.

Philadelphia, Pennsylvania

Day spa in Northeast Philadelphia with a full hydrotherapy circuit of saunas, hammam, cold plunge and pools for a $60 day pass.

Atlanta, Georgia

Korean day spa in Norcross near Atlanta with hot and cold baths, sauna rooms, salt room and a restaurant; day pass runs $30.

Temescal Valley, California

Adults-only hot springs resort in Temescal Valley with 19 outdoor mineral pools, red clay baths, and a cave-like grotto, open daily 9:30am-5pm.

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.

The Hamptons, New York

Oceanfront resort spa in Montauk with a seawater and marine-based treatment menu, hydrotherapy, contrast bathing, and a heated saltwater pool.

Hakone, Kanagawa

Day-use hot spring in Tōnosawa, Hakone, styled like an old farmhouse village, with communal baths and 19 private open-air rental baths.

Hanmer Springs, Canterbury

New Zealand's largest geothermal hot pool complex in Hanmer Springs, with pools from 28°C to 42°C, a lazy river, slides and alpine views.

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.

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.

Los Angeles, California

A women-focused Korean day spa in Pico-Union with steam, salt and ice rooms, open daily 9am to 9pm, with massage and facials open to men too.

Reykjavik, Capital Region

Eight oceanfront geothermal pools in Hvalfjörður, 45 minutes from Reykjavík, plus steam baths, a bistro and guest houses for rent.