Spas with overnight stay

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.

Karlovy Vary, Karlovy Vary Region

Adults-only resort spa on the Březová reservoir near Karlovy Vary, open to hotel guests only, with a two-floor wellness centre and outdoor baths.

Ramona, California

A vacation-rental resort in Ramona whose day-spa access, sauna, steam room and heated pool are reserved for guests staying on the property.

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.

Sayulita, Nayarit

A hillside boutique hotel spa outside Sayulita with sauna, steam room, cold plunge and ocean-view pool, open on a day-pass basis.

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.

Calistoga, California

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

Kamijima, Ehime

An all-inclusive resort on Yugejima island in Setouchi's inland sea, with ocean-view outdoor baths, ocean-front rooms, and a day-pass option.

San Diego, California

Hotel spa on Shelter Island in San Diego with sauna, steam room, and pool, open to guests staying at Kona Kai Resort.

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.

Kyle, Texas

A 88-acre Hill Country resort near Kyle and Wimberley with overnight rooms, a garden spa, pool, hot tubs and day-pass access by reservation.

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.

Calistoga, California

Resort spa at an Auberge Collection hotel in Calistoga with a thermal pool, open to hotel guests only.

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.

Asheville, North Carolina

An overnight-stay forest retreat near Fairview with private cedar hot tubs and a shared sauna pavilion session, not a drop-in day spa.

Adairsville, Georgia

A resort spa at Barnsley Resort in Adairsville, Georgia, offering massage, facials, reflexology, sauna and steam room, open to hotel guests only.

Napa Valley, California

Carneros Resort and Spa is a luxury hotel spa in Napa Valley with outdoor soaking tubs, garden lounges and treatments reserved for overnight guests.

Mykonos, South Aegean

A hotel spa inside Cavo Tagoo Mykonos, open only to guests staying at this luxury resort overlooking the Aegean.

Ein Bokek, Southern District

A large hotel resort spa in Ein Bokek with two spa facilities, a thermal pool and 606 rooms overlooking the Dead Sea, open to hotel guests only.

Puerto Vallarta, Jalisco

A resort spa inside the all-inclusive Dreams Bahia Mita Surf & Spa Resort on Banderas Bay near Punta de Mita, open to hotel guests only.