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.

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.

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.

Tiberias, Northern District

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