Spas with adults only

New York City, New York

A five-treatment-room hotel spa inside The Greenwich Hotel in Tribeca, built around a heated pool and Japanese-influenced design.

San Francisco, California

Upscale day spa on Union Street in San Francisco's Cow Hollow, offering around 20 facial and massage treatments, including a signature Quadruple Lift Facial.

Oaxaca

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

Ojai, California

A small Ojai day spa run by one certified therapist specializing in lymphatic drainage therapy, by reservation.

Elkridge, Maryland

A halotherapy day spa in West Elkridge, near Baltimore, built around a salt cave, massage rooms and a yoga studio, aimed at solo adult visitors.

Las Vegas, Nevada

Adults-only day spa inside Red Rock Resort in Summerlin, open daily 8am-8pm with walk-ins accepted but reservations recommended.

Palm Springs, California

Downtown Palm Springs day spa built around a natural hot mineral spring, with private mineral baths, sauna, steam room and massage.

Sonoma, California

Hotel spa at The Lodge at Sonoma with an outdoor terrace, soaking pool, plunge pool and barrel sauna, open daily 9am-5pm, adults-only, reservation required.

Asheville, North Carolina

A day spa in a converted barn on Horse Shoe Farm near Asheville, offering massage and body treatments amid farm and mountain surroundings.

Napa Valley, California

A single-treatment float spa in Napa offering sensory-deprivation float pods with Epsom salt water, plus dedicated parking and walk-in access.

New York City, New York

Thermal bath circuit and massages in a restored 1883 Tribeca textile factory, with a skylit tepidarium and candlelit thermal pools; reservation required.

San Diego, California

A Korean-style day spa on Convoy Street in Kearny Mesa offering sauna access, body scrubs and massage, open daily 8:30am to 9pm.

Boston, Massachusetts

A Moroccan-style hammam on Route 1 in Peabody offering steam, sauna and exfoliation treatments for adults and couples, reservation only.

San Diego, California

A day spa in University City, San Diego, open since the late 1990s, offering facials, massage and lymphatic drainage with a monthly membership option.

Los Angeles, California

A boutique medical spa in Pico-Robertson focused entirely on facials, from HydraFacial to microdermabrasion, with no body treatments on the menu.

New York City, New York

A no-frills medical spa in Manhattan built around lymphatic drainage therapy and acupuncture, open daily 10am to 9:30pm.

Carmel, Indiana

A no-frills contrast therapy studio in Carmel, Indiana, built around a 30-minute sauna-and-cold-plunge circuit for solo visitors.

Nashville, Tennessee

A Belle Meade day spa and salon offering massage, facials and hair services by appointment, with no walk-in facility pass.

Naples, Florida

Medical spa in North Naples focused on injectables, facials, peels and skin-resurfacing treatments like Morpheus and Votiva.

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.

San Diego, California

A massage-focused day spa in San Diego's Gaslamp District offering Swedish, deep tissue and hot stone sessions daily from 10am to 11:30pm.

Tokyo

Private-room head spa salon in Minami-Aoyama, Omotesando, offering 90- to 210-minute scalp treatments from roughly ¥24,750.

Ojai, California

A small facial studio in Ojai run by esthetician Allison, offering customized facials, RF skin tightening, microcurrent and waxing by reservation.

Zurich

An upscale day spa near Paradeplatz in central Zurich focused on facials, anti-aging treatments and massages for adults.