Spas with thermal pool

Chicago, Illinois

Thermal baths and spa rituals in a restored 1902 factory in West Town, Chicago, open daily for adults-only soaking and massage packages.

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.

Bad Gastein, Salzburg

Thermal baths in Bad Hofgastein with indoor/outdoor pools, bathing lakes, slides, saunas and a sports medicine center, open daily year-round.

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.

Houston, Texas

A Houston day spa near Memorial Park focused on massage and bodywork, with a spa pool, sauna and outdoor retreat, open daily 10am-8pm.

Baden-Baden, Baden-Württemberg

Modern thermal baths in Baden-Baden with indoor-outdoor pools and a Roman-style sauna garden, open daily 8am–10pm, day pass €40.

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.

Portland, Oregon

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

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.

Calistoga, California

A Calistoga hot springs spa built around mud baths, with private couples rooms and mineral pools open daily from 8am to 11pm.

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.

Reykjavik, Capital Region

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

Lake Como, Lombardy

A day spa inside the Castello di Casiglio parkland near Erba, offering a 3-hour pass with heated indoor-outdoor pools, saunas and a Turkish bath; adults and

Austin, Texas

Lakeside day spa near Austin offering a $150 day pass with pools, steam room, sauna and relaxation lounges, open daily 9am–9pm.

Monroe, Utah

Natural hot spring pools fed by mineral water in rural Monroe, Utah, open 24/7 with day-pass soaking and funky bus and cabin lodging on site.

Los Angeles, California

Women-only Korean day spa in Koreatown, LA with saltwater, mineral and cold pools, a salt room, and walk-in day passes.

Edinburgh, Scotland

One Spa is an adults-only day spa in Edinburgh's city centre with a rooftop Hydropool, thermal suite and day-pass access.

Gothenburg, Västra Götaland County

A rooftop pool club and spa spanning two floors of the Jacy'z hotel in Gothenburg, with heated pools, sauna, steam room and a bar-restaurant, open for day

Saturnia, Tuscany

Walk-in thermal park in the Maremma countryside with four outdoor sulfur pools, hydromassage jets and a vascular circuit fed by a 3,000-year-old spring.

Mornington Peninsula, Victoria

Geothermal hot springs and day spa in Fingal on the Mornington Peninsula, with a family-friendly Bath House and an adults-only Spa Dreaming Centre.

Sirmione, Lombardy

A lakeside thermal spa in Sirmione with indoor and outdoor pools fed by sulphurous spring water, a vascular circuit, saunas, and a day-pass option.

Seattle, Washington

A clothing-optional outdoor hot pool, sauna and sun deck in Seattle's West Woodland, open to walk-ins for three-hour day visits.

Auckland

Hotel day spa at Pullman Auckland CBD with a 25m heated pool, sauna, steam room, jacuzzi and gym plus massage and facial treatments.

New York City, New York

A budget-friendly Korean-style bathhouse in Queens with indoor and outdoor hydrotherapy pools, saunas and a restaurant, open to walk-ins daily.