Spas with thermal pool

San Francisco, California

A Japantown bathhouse open for 50+ years, with a Japanese-style thermal pool and relaxation lounge, reservation required, adults only.

Austin, Texas

Adults-only resort spa on Lake Austin offering all-inclusive overnight stays and limited day passes to pools, saunas, steam rooms and lake activities.

The Hamptons, New York

Adults-only destination spa and 12-room retreat in Water Mill, offering hydrotherapy, yoga, spa treatments and overnight stays by reservation.

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.

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.