Rio's calls itself London's leading naturist health spa, and it has the fixture status to back the claim: a purpose-built spa on Kentish Town Road, open seven days a week for liberated people aged 21 and over — its own phrasing — rather than a club that opens on selected nights.

The facilities read like a full spa floor: three steam rooms, two sauna cabins, three large jacuzzis and a plunge pool, alongside a relaxation area, a television lounge, a host of relaxation rooms, an outdoor garden and a smoking area.

Hours are long: Monday to Wednesday from 12:00 to midnight (last entry 22:00), Thursday to Saturday from 12:00 through to 07:00 the next morning (last entry 04:00), and Sundays 12:00–22:00 (last entry 20:00). One rule stands out and is strictly enforced: on Saturdays between 18:00 and midnight, admission is mixed couples only.

There is deliberately no membership — Rio's calls central London too full of visitors for one to be fair, and runs pay-as-you-use instead: turn up, pay, and use the spa. Entry prices are on the spa's own site and at the door. Browse our London guide for the city's other saunas and clubs.