Spas with reservation required

Amsterdam, North Holland

A day spa inside a former bank vault in central Amsterdam, with pool, whirlpool and a canal-view gym; adults-only, day pass by reservation.

Längenfeld, Tyrol

A large thermal bath and 4-star hotel spa in the Ötztal valley near Längenfeld, with indoor-outdoor pools, a sauna garden and a dedicated kids' water world.

Singapore

Garden-set day spa inside Bishan Park 2 with 12 treatment rooms, outdoor baths, massages and facials using Elemis and Skinceuticals products.

San Francisco, California

Adults-only Russian bathhouse in San Francisco's India Basin with steam rooms, cold plunge, rooftop deck and a café, open daily except Tuesday.

Palm Springs, California

Adults-only hot springs resort on Miracle Hill in Desert Hot Springs with private mineral tubs, a Finnish sauna, salt room and 35 spa treatments.

Seattle, Washington

A private floating bathhouse on Seattle's Lake Union, booked out entirely for one group of up to 12 for sauna, cold plunge and hot tub rounds.

Miami, Florida

A luxury day-pass wellness circuit inside Carillon Miami Wellness Resort, with sauna, steam, cold plunge and thermal pools in North Beach.

Istanbul

A working Ottoman hammam built in 1741 in Istanbul's Fatih district, offering traditional bath rituals with no day-pass option, only full treatments.

Marrakech, Marrakesh-Safi

A 1,200-square-metre hotel spa at Selman Marrakech built around the Chenot method, with hammams, pools and multi-day wellness programmes.

Jackson Hole, Wyoming

Rooftop hotel spa at Hotel Terra in Teton Village offering facials and massages, with hot tub and steam room access included only when you book a treatment.

Hot Springs, Arkansas

A combined day spa and med spa in Hot Springs offering massages, facials, laser treatments and lunch-inclusive packages by reservation.

Durango, Colorado

A hot springs resort in the Animas Valley near Durango, Colorado, with 32 mineral pools, cold plunges, a lap pool and private cedar soaking tubs.

Palm Springs, California

Moroccan-themed inn in Desert Hot Springs with natural mineral hot springs, a spring-fed pool and day-pass access from 9am to 4pm.

Palm Springs, California

Hotel spa inside the Avalon in Palm Springs, open Thursday through Monday, with a $75 day pass covering jacuzzi, sauna, cold plunge and steam rooms.

New York City, New York

Hotel spa inside Thompson Central Park combining massages, facials and body treatments with daily fitness classes and private saunas, near Central Park.

Bormio, Lombardy

Adults-only hotel spa near Bormio with thermal pools, a relaxation lounge and a 13-treatment menu; day passes start around €44 for evening entry.

Williamstown, Massachusetts

Day spa in a converted 1762 grist mill on the Green River in Williamstown, offering massage, facials and a private outdoor hot tub.

Scottsdale, Arizona

A moderately priced day spa in South Scottsdale with lake-view suites, massage and facials, plus a dedicated couples treatment room.

Miami, Florida

A Peruvian-themed day spa inside the Victor Hotel on Ocean Drive, South Beach, with a hamam, steam room, sauna and a couples suite.

Oslo

Waterfront sauna spot on Aker Brygge with shared and private saunas, sea bathing, and sauna boat trips on the fjord.

Bursa

A historic thermal bathhouse and small hotel in Bursa's Kükürtlü district, with separate men's and women's hamams, day passes, and overnight stays.

Portland, Oregon

A membership-driven wellness club in downtown Portland with hot pools, sauna, steam room and cold plunge, plus massage, skincare and fitness classes.

Phuket

Adults-only Ayurvedic resort on a Rawai hillside with doctor-led Panchakarma programs, a saltwater pool and 47 private villas.

French Riviera, Provence-Alpes-Côte d'Azur

Hotel spa inside Nice's Le Negresco with hammam, sauna and fitness center; outside guests must book a 90-minute treatment to use the wet areas.