Spas with thermal pool

Shibu Onsen, Nagano

A ryokan in Shibu Onsen with indoor and outdoor hot-spring baths fed by two blended mineral springs, open only to overnight guests.

Scottsdale, Arizona

A luxury resort spa in Paradise Valley near Scottsdale with outdoor baths, a thermal pool and a relaxation lounge, open to hotel guests only.

Reykjavik, Capital Region

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

Tyrol, Bavaria

Hotel spa in Kreuth-Reitrain near Tegernsee with a 3,000 sqm onsen-style bathing area, hot and cold pools, saltwater pools and sauna, open on a day-pass basis.

Ourense, Galicia

An outdoor hot-springs spa in Ourense with thermal pools, walk-in day passes, and hours that run late on weekends.

Bath, England

A small open-air thermal pool in a separate building from Thermae Bath Spa's main complex, with its own changing rooms and day-pass access.

Lake Tahoe, California

Hotel-only spa at a lakefront resort in South Lake Tahoe, with an outdoor heated pool, Jacuzzi and treatment rooms aimed at couples.

Pagosa Springs, Colorado

Day-pass hot springs resort in Pagosa Springs with over 50 mineral pools fed by the Mother Spring, plus a spa for massages and body treatments.

Tucson, Arizona

A hotel spa at an 80-acre Sonoran Desert resort in Tucson, open to overnight guests, with three pools, hot tubs, sauna and yoga classes.

Buxton, England

A hotel spa built into Buxton's historic Crescent, centred on a thermal pool, hydrotherapy circuit and salt room, open to hotel guests only.

Saturnia, Tuscany

A hotel spa near Terme di Saturnia with an infinity pool, hot tub, rooftop terrace and restaurant, offering day passes for non-guests.

Arima Onsen, Hyogo

Hotel spa in Arima Onsen with Arima's rare iron-rich "ginsen" waters, outdoor baths, sauna and jacuzzi, run as an all-inclusive overnight stay.

Santorini, South Aegean

Natural sulfur hot springs at the foot of a volcanic islet in the Santorini caldera, reached by boat and accessed by swimming from the water.

Abano Terme, Veneto

A day-pass thermal spa in Abano Terme with an outdoor thermal pool, set at the foot of the Euganean Hills in the Veneto countryside.

San Diego, California

Hotel spa at Carté Hotel San Diego Downtown with a heated saltwater pool, whirlpool, 28,000 sq ft fitness club with sauna and steam room, open to guests only.

Chiang Mai, Northern Thailand

A hotel spa inside the Four Seasons Resort Chiang Mai in Mae Rim, with sauna, steam room, cold plunge and thermal pools set among rice paddies, open to resort

Abano Terme, Veneto

A family-run thermal spa complex in Abano Terme with two hotels, thermal pools, mud therapy and a day-pass option for non-guests.

Philadelphia, Pennsylvania

A hotel spa inside the Four Seasons Comcast Center tower in Center City Philadelphia, open to overnight guests with an infinity pool and skyline views.

Austin, Texas

A lakeside resort spa on Lake Travis in Lakeway, Texas, with pools, outdoor baths and treatments, open only to hotel guests.

Bad Blumau, Styria

Rogner Bad Blumau is a Hundertwasser-designed thermal resort in Styria with geothermal pools, outdoor baths and hotel-guest-only access.