Spas with reservation required

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.

Daylesford, Victoria

A rammed-earth house on 80 hectares near Daylesford, rented whole for up to 10 adults, with in-room massage and a two-night minimum stay.

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.

Kuala Lumpur

An onsen-style day spa in Kampung Baru, Kuala Lumpur, with thermal pools, sauna, steam room and couples treatments.

Oslo

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

Boston, Massachusetts

A Finnish kelo-log banya in Newton with sauna, steam room and cold plunge, alternating men's and women's days, day passes from $69.

Denver, Colorado

A small European-style bathhouse in Denver where you rent a private sauna by the hour and share a cold plunge, cold waterfall bucket and steam room.

Nashville, Tennessee

A community sauna studio in East Nashville's Porter Road corridor with communal and private sauna rooms plus an outdoor pop-up cold plunge.

Mexico City, Quintana Roo

A Japanese-style hotel spa in Mexico City's Cuauhtémoc district with tatami suites, outdoor onsen baths and a $2,080 day pass for couples.

Cotswolds, England

A woodland sauna and ice bath venue near Northleach in the Cotswolds, offering communal and private heat-and-cold sessions plus occasional workshops.

Asheville, North Carolina

A Japanese-inspired destination spa on a mountainside outside downtown Asheville, built around private outdoor salt hydrotherapy tubs and massage.

London, England

A Russian-style banya bathhouse in Belgravia offering oak-lined steam rooms, cold plunge pools and leaf-massage rituals, with day passes by reservation only.

Port Douglas, Queensland

Ayurvedic-style massage and bathhouse studio in Port Douglas offering couples treatments, yoga and reformer Pilates, bookings required with no walk-ins.

Merano, Trentino-South Tyrol

An adults-only, guests-only longevity retreat and hotel spa in Merano with a medical-led wellness institute and private suite treatments.

Gold Coast, Queensland

A 90-minute hydrotherapy circuit in Southport with a Finnish rock sauna, 5° ice baths and hot/cold magnesium pools, day pass $49.

Luhačovice, Zlín Region

A destination spa in Luhačovice built around mineral springs, offering medical cures, sauna world, outdoor whirlpools and fitness, open daily 7am–8pm.

Wulai, New Taipei

A hilltop Wulai B&B with sodium bicarbonate hot-spring baths in every room and an outdoor infinity pool, geared toward couples.

Carefree, Arizona

A 20-plus-acre desert wellness resort in Carefree, Arizona, with a full spa, pools, and 100-plus weekly fitness and mindfulness classes open to day visitors by

Seattle, Washington

Private-rental bathhouse and sauna in Capitol Hill, Seattle, open daily 8am–midnight, clothing optional and booked by reservation only.

Koh Samui, Surat Thani

Kamalaya Koh Samui is an adults-only destination spa and wellness retreat on Laem-Set Rd with over 100 treatments, thermal circuits and multi-day health

Oaxaca

A traditional four-door temazcal steam ceremony about 15-20 minutes outside Oaxaca city, paired with an ice-water plunge and overnight rooms.

Cotswolds, England

A wood-fired riverside sauna at Whichford Mill in the Cotswolds, with a cold-plunge bath, river dipping, and both private and communal sessions.

Ubud, Bali

An adults-only wellness retreat on Ubud's Ayung River offering multi-day healing programmes, thermal circuits and plant-based cuisine by reservation only.

Mariánské Lázně, Karlovy Vary Region

Hotel spa inside Mariánské Lázně's Ensana resort complex, open daily 8am–5pm for guests with reservations.