Spas with thermal pool

Guanziling, Tainan

A grayish mud hot spring in Baihe, Tainan, with outdoor baths and a thermal pool, open daily from 9am to 11:30pm.

Asan, South Chungcheong

Hot springs resort spa in Asan with thermal pools, sauna and a relaxation lounge, open daily on a walk-in day-pass basis.

Redstone Historic District, Colorado

A ranch property in Colorado's Crystal River Valley with three tiered natural hot springs pools open to day visitors and overnight guests alike.

Băile Felix, Bihor

A thermal baths complex in Băile Felix with outdoor and indoor pools, open daily with walk-in access and no membership required.

Manuel Antonio, Puntarenas

A destination spa with outdoor thermal pools near Manuel Antonio, Costa Rica, open daily with reservations required.

Thermopolis, Wyoming

Free public bathhouse in Thermopolis, Wyoming, with indoor and outdoor mineral soaking pools held at 104°F, open seven days a week.

Jemez Springs, New Mexico

Walk-in outdoor mineral hot springs in Jemez Springs, NM, with four pools kept between 98 and 105°F and a $25 one-hour day pass.

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.

Asan, South Chungcheong

A hot springs facility in Asan with thermal pools, hot tubs and saunas, open to walk-ins and suited to families.

Reykjavik, Capital Region

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

Jerusalem, Jerusalem District

A hotel spa in Jerusalem with sauna, hot tub and thermal pool, open to walk-ins and day-pass guests most days of the week.

Sáchica, Boyacá

Natural thermal pools and a relaxation lounge at the edge of Villa de Leyva, open daily except Wednesday with day passes for families and couples.

Ourense, Galicia

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

Bad Ragaz, St. Gallen

A resort thermal spa in Bad Ragaz with indoor and outdoor thermal pools and sauna, open daily 7:30am–8pm, reservation required for day passes.

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.

Catskills, New York

A Catskills retreat center with a Tibetan-style spa offering sauna, steam, pools and cold plunge, built around overnight stays and group programs.

Papallacta, Napo

A budget-friendly thermal pool complex in Papallacta with an on-site restaurant, open daily from 6am to 8pm, walk-ins welcome.

Calistoga, California

MoonAcre Spa & Baths is a day spa in Calistoga with a thermal pool, hot tub and sauna, open daily 9am–5pm and geared toward families and couples.

Ranong

A budget thermal-bath spot in Ranong with a soaking pool and an on-site café, open daily 9am to 10pm, walk-ins welcome.

Bad Blumau, Styria

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

Tiberias, Northern District

A budget-friendly hot springs in Tiberias with a thermal pool, open daily except Monday, day passes and walk-ins welcome.