Spas with thermal pool

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.

Oaxaca

An all-inclusive beachfront resort spa in Huatulco with a sauna, steam room and thermal pools, open only to hotel guests.

Miami, Florida

A hotel spa at Eden Roc Miami Beach in Mid-Beach with sauna, steam room, cold plunge and thermal circuits, open to resort guests only.

Calistoga, California

A 25-room Sonoma hotel in Forestville with a spa barn offering sauna, steam and pools, mainly for overnight guests.

Afyonkarahisar

Resort hotel in Afyonkarahisar built around thermal pools, spa treatments and physical therapy, open to hotel guests.

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.

Sedona, Arizona

A 23-casita destination spa resort inside Sedona's Boynton Canyon, open to overnight hotel guests 16 and older for multi-day wellness journeys.

San Diego, California

A hotel spa on Mission Bay in San Diego with sauna, steam room, cold plunge and thermal pools, open only to resort guests.

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.

Tulum, Quintana Roo

Resort spa at an all-inclusive Tulum beach hotel, with hydrotherapy, jungle and beach-side treatment cabins, open to hotel guests only.

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.

Palm Beach, Florida

Oceanfront resort spa at the Four Seasons Palm Beach, open to hotel guests only, with thermal pool, relaxation lounge and ocean-view pool deck.

Big Island, Hawaii

A hotel spa at Hilton Waikoloa Village on Hawaii's Big Island, with a pool and thermal pool, open to hotel guests.

West Bay, Bay Islands Department

A beachfront resort spa on Roatán's West Bay Beach with a hydrotherapy circuit, thermal pool and ocean views, open only to hotel guests.

Austin, Texas

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

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.

Bad Blumau, Styria

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

Palm Springs, California

A hotel-guests-only desert resort in Desert Hot Springs built around natural mineral hot spring pools, with spa treatments and overnight stays.