Spas with upscale

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.

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.

Los Angeles, California

Hotel pool and hot tub deck at a Tapestry by Hilton near SoFi Stadium and the Kia Forum in Inglewood, open to registered guests only.

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.

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.

Taos, New Mexico

A boutique skin and body studio in Taos offering facials, lymphatic massage, Endermologie and head spa treatments by appointment.

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.

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.

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.

Adairsville, Georgia

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

Scottsdale, Arizona

A hotel spa at the 65-acre Fairmont Scottsdale Princess resort in North Scottsdale, open to overnight guests with sauna, steam room and pool access.

Catskills, New York

Adults-only resort spa in the Catskills with sauna, hot tub, yoga studio and overnight stays for hotel guests only.

Huntington Beach, California

An adults-only hydrotherapy circuit with hot tub, sauna and steam room for guests staying at this beachfront Hyatt Regency resort in Huntington Beach.

Austin, Texas

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

Bad Blumau, Styria

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

Carmel-by-the-Sea, California

A golf-and-wellness resort spa in Carmel Valley, open to hotel guests only, with a heated pool, fitness cabanas and treatments at Spa Adeline.

Sedona, Arizona

A boutique resort spa in Sedona with a heated pool, hot tub, yoga and massage, open only to hotel guests.

Islamorada, Florida

Hotel spa at Three Waters Resort and Marina in Islamorada, Florida, with outdoor baths, a pool and ocean views, open to resort guests.

Yufuin, Oita

A small hillside ryokan near Yufuin's town center where every room has its own half-open-air bath filled with 100% source hot-spring water and a view of Mt.