Spas with thermal pool

Boston, Massachusetts

A hotel spa inside Mandarin Oriental, Boston's Back Bay property, open to hotel guests only, with sauna, steam room, pools and a cold plunge.

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.

Los Angeles, California

A hotel spa at Shade Hotel Redondo Beach with sauna, steam, pools, cold plunge and thermal circuits, open to hotel guests overlooking the marina.

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.

Chianciano Terme, Tuscany

Hotel spa in Chianciano Terme open to non-guests, built around a 450 sqm holistic water, color and massage circuit.

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.

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.

Spa, Liège

Hotel spa in the town of Spa, Belgium, with a thermal pool, relaxation lounge and restaurant, open to day-pass visitors, not just hotel guests.

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.

Atami, Shizuoka

A hotel spa in Atami with a thermal onsen pool, open only to overnight guests staying at Fufu Atami.

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.

Santa Barbara, California

A hotel spa inside Hotel Californian in Lower State, Santa Barbara, with a thermal pool and relaxation lounge, open to hotel guests only.

Scottsdale, Arizona

A resort spa at JW Marriott Phoenix Desert Ridge with a thermal pool, relaxation lounge and on-site café, open to hotel guests and day-pass visitors.