Spas with reservation required

The Hamptons, New York

A moderate-priced, adults-only day spa in Hampton Bays focused on massage, with a salt room and red light therapy, by appointment only.

Penang

An adults-only villa resort spa near Kepala Batas, Penang, with 18 private villas, spa treatments and plant-based dining; reservation required.

Bad Blumau, Styria

Rogner Bad Blumau is a Hundertwasser-designed thermal resort in Styria with geothermal pools, outdoor baths and hotel-guest-only access.

Yufuin, Oita

A small hillside ryokan near Yufuin's town center where every room has its own half-open-air bath filled with 100% source hot-spring water and a view of Mt.

Tulum, Quintana Roo

Beachfront resort in Tulum pairing overnight stays with spa treatments, yoga and fitness classes, open to hotel guests only.

Denver, Colorado

Private Russian banya spa in Denver's Cheesman Park offering banya sessions, massage and body treatments by appointment since 1995.

Big Sur, California

Adults-only hotel spa at Ventana Big Sur with ocean-view treatment rooms, outdoor cabanas for couples, and a 24-hour fitness and yoga space.

Orlando, Florida

Affordable day spa on Orlando's International Drive offering Thai massage, facials, reflexology, and couples treatments alongside a steam room and sauna.