Spas with reservation required

The Colony, Texas

A day-soaking spa in The Colony with mineral pools at varying temperatures, seven saunas, cold plunges and a poolside café.

Glenwood Springs, Colorado

A natural geothermal vapor cave in Glenwood Springs, Colorado, where visitors steam in ancient rock chambers and add massages, mineral baths or body treatments.

Park City, Utah

A reservation-only day spa in Sandy, Utah, built around scalp spa treatments, plus sauna, steam, cold plunge and thermal pools.

New York City, New York

Midtown Manhattan day spa with 13 treatments, a jacuzzi and package deals for couples, birthdays and bachelorette groups.

New York City, New York

A Midtown East day spa in Manhattan offering massages, facials, mani-pedis, a hot tub lounge and package deals for couples, birthdays and bachelorette groups.

Tallinn, Harju County

A small hotel spa in central Tallinn with three treatment rooms, two saunas and a Japanese pool, offering massages and facials by appointment.

Miami, Florida

Medical spa in Miami's Edgewater doing Botox, fillers and facials, plus a sauna, steam room and thermal pool for aftercare.

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.

Vail, Colorado

Hotel spa inside Park Hyatt Beaver Creek with a 5-step hydrotherapy circuit, sauna, steam room and day-pass access to massages, facials and fitness classes.

Soufrière

Hotel spa at Ladera on the Pitons ridge in Soufrière, with day passes, couples treatments and volcanic mineral pool access.

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.

Sedona, Arizona

A Sedona day spa focused on deep tissue massage, fascia work and facials, with a sauna, steam room and thermal pool on site.

Los Angeles, California

Day spa in Woodland Hills with a hydrotherapy circuit, massage, facial and body treatment menu, open daily 8am-10pm (closed Tuesdays).

San Diego, California

Day spa in San Diego's Hillcrest neighborhood offering steam room, dry sauna and jacuzzi, open seven days with free parking nearby.

San Diego, California

A La Jolla medical spa specializing in lymphatic drainage, colon hydrotherapy and detox treatments, open since 1993, adults only, by reservation.

Lake Tahoe, California

Lakeside spa inside Tahoe Lakeshore Lodge in South Lake Tahoe, with a hot tub, polar plunge and dry sauna, by appointment only.

Granada, Andalusia

A traditional-style hammam in central Granada with a heated thermal pool and relaxation lounge, open daily from 9am to midnight.

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

Chicago, Illinois

Upscale day spa in Lincoln Park, Chicago, where booking any treatment unlocks all-day access to a hydrotherapy circuit, thermal suite and outdoor terrace.

Koh Phangan, Surat Thani

Day spa in Ban Tai, Koh Phangan, with massages, baths and multi-hour packages for solo guests or couples, plus private suites and a sauna.

Rogaška Slatina, Savinjska

A reservation-only medical spa and clinic in Rogaška Slatina combining diagnostics, wellness treatments and the region's magnesium-rich Donat mineral water.

Ras Al Khaimah

A moderate-priced day spa in Ras Al Khaimah's Al Maireed area offering hammam, massage and exfoliation treatments, open daily 9am to 9pm.

Amalfi Coast, Campania

An adults-only day spa in Minori on the Amalfi Coast built around a thermal pool, open daily 11am to 8pm by reservation.

Chicago, Illinois

A West Town day spa built around a beer soak, with sauna, steam room, salt room and thermal pool for couples or solo visits.