Spas with groups

Dogo Onsen, Ehime

A roughly 3,000-year-old public hot spring bathhouse in Matsuyama, designated an Important Cultural Property, open daily with walk-in day passes from 700 yen.

San Miguel de Allende, Guanajuato

Family-friendly hot springs park near San Miguel de Allende with indoor and outdoor thermal pools, a kids' splash area, and day passes for walk-ins.

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.

Reykjavik, Capital Region

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

Ischia, Campania

Family-run thermal pool park on Ischia's Maronti beach, open since 1973, with three sulfur-water pools, a sauna and direct beach access.

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.

Rishikesh, Uttarakhand

A compact Ayurvedic spa and yoga retreat near Laxman Jhula in Rishikesh, offering six treatments including Shirodhara by appointment only.

Shibu Onsen, Nagano

Reservation-only private hot spring and sauna suites at a Nagano brewery complex, built around a craft beer bathing plan for two to four guests.

Arima Onsen, Hyogo

A moderately priced onsen bathhouse in Arima Onsen, Kobe, with a forest sauna, a large outdoor bath, yoga and an award-recognized restaurant.

Ho Chi Minh City

A Korean-style jjim jil bang in Ho Chi Minh City with six heated rooms, a Dead Sea mineral soaking pool, and massage, hair-wash and facial services.

Calistoga, California

A 1952 Calistoga hot springs resort with three mineral pools at 85, 95 and 104°F, mud baths, overnight rooms and a day-pass option.

Húsavík, Northeastern Region

Geothermal seawater baths built into the cliffs above Skjálfandi bay in Húsavík, with walk-in day passes and views toward the Arctic horizon.

Thatcher, Idaho

A riverside hot springs in Thatcher, Idaho, with outdoor thermal pools, day passes, and overnight stays in yurts, cabins, or tents.

Asan, South Chungcheong

A hot-springs day spa in Asan's Dogo hot-spring district, open daily with a day pass for walk-in soaking and family visits.

Asheville, North Carolina

Ayurvedic destination retreat in the Blue Ridge Mountains near Asheville, with day-pass spa visits and multi-night panchakarma cleanses by reservation.

Băile Felix, Bihor

Strand Apollo-Felix is a year-round thermal pool complex in Băile Felix, Romania, with indoor and outdoor pools open daily from 8am to 8pm.

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.

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.

Palm Springs, California

A 10-room mineral hot springs hotel in Desert Hot Springs near Palm Springs, offering day passes to its 120°F spring-fed pools, sauna and massage rooms.

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.