Spas with thermal pool

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.

Buenos Aires

A hotel spa inside the Palacio Duhau-Park Hyatt in Barrio Norte, open only to hotel guests, with Mapuche-inspired treatments and a semi-olympic pool.

Ainsworth, British Columbia

A lakeside hot springs resort in British Columbia's Kootenays with public thermal pools, a spa, restaurant and overnight rooms, closed Tuesdays.

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.

Melbourne, Victoria

A Japanese-inspired bathhouse in central Melbourne with mineral baths, a cold plunge and a salt room, open late most nights on a walk-in or day-pass basis.

Hot Springs, Arkansas

Adults-only hotel spa at Oaklawn Resort in Hot Springs with vitality pools, heated loungers, needle showers and treatment-based access only.

Las Vegas, Nevada

Adults-only hotel spa at Resorts World Las Vegas with a six-pool hydrotherapy circuit, salt room, and a themed Aufguss sauna show on weekends.

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.

New York City, New York

A Flatiron bathhouse with six thermal pools, a banya, dry and infrared saunas, a steam room and a salt pool, day pass from $39.

Tucson, Arizona

A luxury all-inclusive wellness resort in Tucson's Hidden Valley with four pools, a hydrotherapy circuit, cold plunges and over 200 spa treatments.

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.

Lake Tahoe, California

Family-friendly hot springs resort near Lake Tahoe with outdoor pools, private indoor soaking rooms and saunas, open daily on a walk-in basis.

Riviera Maya, Quintana Roo

Adults-only hotel spa at Devossion by Live Aqua in Playa del Carmen, open daily 8am-8pm, with sauna, steam room and pools for resort guests.

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.

Palm Springs, California

Moroccan-themed inn in Desert Hot Springs with natural mineral hot springs, a spring-fed pool and day-pass access from 9am to 4pm.

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.

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.

Napa Valley, California

Resort spa at Stanly Ranch in Napa Valley offering hyperbaric oxygen therapy, cold plunge, sauna, steam room and salt therapy, with day passes available.

Tucson, Arizona

A resort spa in Tucson's Starr Pass area with a saline lap pool, sauna and fitness center, plus signature treatments from $159 for hotel guests.

Hot Springs, Arkansas

A nine-suite boutique hotel on Bathhouse Row with in-room soaking tubs fed by hot spring mineral water, open only to overnight guests.

Valle de Bravo, State of Mexico

A forest hotel spa outside Valle de Bravo built around a hydrotherapy circuit of hammam, sauna, cold pool and contrast pools, open to overnight guests only.

Houston, Texas

Upscale day spa at The Houstonian in Houston with 22 treatment rooms, soaking pools and a sundeck; pool access comes with a 50-minute-plus treatment, not a

Duluth, Georgia

A 24-hour Korean bathhouse in Duluth with a $30 day pass, sauna rooms, cold plunge, thermal circuits and a junior Olympic pool.