Spas with upscale

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.

Fort Lauderdale, Florida

Mokara Spa inside the Omni Fort Lauderdale Hotel has the area's only hammam, plus treatment rooms, a pool deck and rooftop bar, open to hotel guests only.

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.

Park City, Utah

Serenity Spa is the treatment center inside Westgate Park City Resort, a ski-in villa resort with a year-round indoor/outdoor pool, sauna and steam room for

Adairsville, Georgia

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

The Hamptons, New York

A 29-room boutique hotel in Southampton with a poolside bathing club, relaxation lounge and restaurant, 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.

Fort Lauderdale, Florida

A hotel spa at the Fort Lauderdale Marriott Harbor Beach Resort, open to hotel guests, with ocean views, a relaxation lounge and an on-site restaurant.

Sint Eustatius

A 40-acre dive-and-stay resort on Sint Eustatius with a pool, restaurant and shuttle service to its dive center, open only to overnight guests.

Napa Valley, California

Spa Terra is the cave-set spa at Meritage Resort in Napa Valley, open to hotel guests with pools, a relaxation lounge and on-site dining nearby.

Scarborough

A boutique hillside hotel above Bacolet Bay in Scarborough, Tobago, with an infinity pool and ocean views, built around a converted 150-year-old Donkey Cart

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.

Scottsdale, Arizona

A resort spa at JW Marriott Phoenix Desert Ridge with a thermal pool, relaxation lounge and on-site café, open to hotel guests and day-pass visitors.

Austin, Texas

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

Ojai, California

Hotel spa at the Ojai Valley Inn resort, open only to overnight guests, with pool and restaurant access on site.

Palm Springs, California

A hotel spa at Palm Springs' Riviera Resort & Spa, open only to overnight guests and paired with a pool, restaurant and bar.

Puerto Vallarta, Jalisco

An all-inclusive family resort on Puerto Vallarta's hotel-zone beach, with a spa (opening soon) offering massages, facials and other treatments for guests only.

Hudson Valley, New York

Hotel spa inside a restored convent in Peekskill, overlooking the Hudson River, open only to overnight guests of The Abbey Inn.

St. Andrews, New Brunswick

A hotel spa at The Algonquin Resort in St. Andrews, New Brunswick, offering ocean-view relaxation space with day-pass access for non-guests.

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.