Spas with reservation required

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.

Mauritius

Moroccan hammam and beauty salon in Grand Baie, Mauritius, offering steam rituals, scrubs and massages with sauna and hot tub, reservation only.

Fez, Fès-Meknès

Family-run hammam and day spa in Fez's Ville Nouvelle offering traditional scrub-and-massage packages, a jacuzzi, sauna and à la carte beauty treatments.

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.