The young Turkish guy stands up, his hard-on pointing straight out like a divining rod. His mates all cheer as though his erection is worthy of some kind of award. It's 1AM in the main jacuzzi at Rio's Relaxation Spa, Kentish Town. Couples night runs from 7PM until 12AM, but it looks like the swinging is still in full swing, given that right now there are three couples having sex in the water, with eight – maybe nine – blokes enjoying the bubbles and pretending not to watch.
Rio's, a ten-minute walk from Camden High Street, is the punchline to plenty of jokes about dodgy drunken activities ("Ended up in Rio's, did you?"), but it's probably more talked-about than visited. With its iconic, slightly tacky exterior, its photographs of palm trees and sparkling seas at odds with the grimy urban location, there's a widely held belief that the "relaxation" on offer isn't limited to the saunas, steams rooms and plunge pools – that the massages all end very happily indeed.
What actually happens when you visit Rio's is this: you go to the small reception window, where you pay an entrance fee (£21 for single guys, £8-£10 for single women and £21-27 for couples, depending on the time of day) and are given a towel and a locker key. Then, after a quick frisk by the security guard, you pass through a heavy door. Having stripped nude in the extremely basic changing rooms, you walk into the club via the TV room. Here, the aesthetic you see on the shopfront is developed even further: there's dark mahogany panelling, dusty cheese plants and terrible 60s-style, soft-focus "erotic" artwork on the magnolia walls.
You'll get your first glimpse of nudity here as people without clothes recline on white plastic loungers watching football or movies – Snow White with Anne Hathaway, King Arthur with Ray Winstone. There's a strange disconnect at first between the kids' blockbusters on the HD TV and the copious amount of bush and genitalia casually displayed about the place. But as you enter a wide oblong corridor with two jacuzzis and copious steam rooms and saunas under dim blue lighting, you realise that the tension between the oddly familial, friendly atmosphere and the promise of sex that hovers over everything is what makes Rio's special.
The late night crowd here is diverse. There are Afro-Caribbean, Turkish, Russian, Greek, Japanese and Indian revellers, either with white bath towels wrapped around their waists, or – more frequently – nothing at all. Rio's is predominantly straight, but it has a strong gay following, too.
Let's talk more about nudity. The club has a fully-naturist policy on most nights. When you arrive you will be faced with a smorgasbord of cocks (soft and hard), vaginas and asses – some more attractive than others. For the first few minutes this can be disconcerting, as though you have suddenly dropped into a Through the Looking-Glass world where, for some reason, everyone's decided to strip off and pretend it's all cool. After a short while, though, you become accustomed to it, in the same way you quickly get used to the low lighting. Still, a hefty guy's hairy balls swinging by your face as he hauls ass out of the plunge pool is enough put a damper on any hopeful fantasies you may have had before you arrived.
The main room contains a large jacuzzi that could probably hold 20, maybe more, and a swimming pool. The high, whitewashed wooden ceiling gives it a clubhouse feel. There is something oddly relaxing about kicking back, enjoying the bubbles and observing – a kind of advanced-level people watching. There's a social vibe here and most punters know not to overstep the mark. But one mountainous bloke, his stomach skin flabby and tent-like, distended by his huge pot belly – his man-boobs heavy orbs sliding away from one another – moves to sit next to a cute Greek couple who've just arrived. The big man keeps glancing furtively at the girl. She seems to notice, and looks annoyed. A persistent twitch in his shoulder suggests he's wanking discretely beneath the water. The chlorine is eye-stingingly strong – just as well.
"There was this rich Russian bloke who came here regularly with his girlfriend. No telling how many blokes would go through her in the steam room."
Swinging – or wife-swapping – went mainstream in Britain in the 1970s, so given the free love feel of Rio's, I'm surprised to learn that it only came into being in 1989. Trevor, the owner, saw how popular spas were in Europe and set about opening his own in formerly down-at-heel Kentish Town, which – at the time – was best known as a good place to go if you wanted to buy a gun in a pub. Things were better at the club in the old days, according to Jim, a Geordie I get chatting to in the pool.
"You should have been here 20 years ago – a lot more action then," he promises. "You still see some sights, though. There was this Russian bloke who came here regularly for a while with his girlfriend. He was 70 and rich; she was 25 and hot as hell. He'd go downstairs for a massage for 90 minutes, and she'd have some fun while he was gone. No telling how many blokes would go through her in the steam room. She was clever – she'd time it just right so her fella never found out."
There's definitely a lot of fun to be had here, if you arrive at the right time and know where to look. To the back of the swimming pool, a dark corridor illuminated by low red lights leads out to the garden. Along the way are three or four private rooms, each with a bed and a paper towel dispenser on the wall. Stern signs warn you not to enter uninvited if they are closed, but sometimes it's not necessary to try and inveigle your way in. During the evening, solo men and women often sit in them with the doors open, staring invitingly at passers-by.
"It's important you arrive early. With a girl. It doesn't matter if she's ugly. It's just important you bring her so you can fuck other girls."
According to a Vladimir Putin lookalike in a Speedo, to maximise your chances for adult fun you need to come in a mixed couple.
"It's important you arrive early. With a girl. It doesn't matter if she's ugly. It's not so important. It's just important you bring her so you can fuck other girls," he advises, romantically.
Vlad comes here every other week. He gets lucky most visits, but it's definitely hit and miss.
"Sometimes sex, yes – sometimes no. You take your chances. Better you arrive with a pretty girl."
If all of this sounds a little seedy, then that's not the whole picture. I hear one couple discussing the invitation they're received to a fondue party. Another guy is drying his girlfriend's hair by the mirrors outside the changing rooms. Rios, it seems, has a tender side, too.
"I met my wife here 20 years ago," the elderly Geordie confides. "She has one of the greatest talents a woman can possess."
"She has no gag reflex in her throat."
"It's a great quality to have."
"Sure is. We get on very well. We have an understanding. I love seeing her go down on other guys. There used to be this Moroccan fella who'd come here every week. Ugly as sin he was, but with a huge cock. It was great, watching her make that thing disappear."
It's a level of candour you wouldn't encounter elsewhere, but I'm glad he's comfortable enough to share.
"Where's she now?" I ask.
"She's gone home," he says.
By 3AM, the pickings are slim – just a few couples who don't seem particularly inclined to put out, and a legion of thirsty blokes, including the cuddly wanker from earlier.
For a long-time swinger like him, you'd think Rio's must be paradise, a celestial oasis in the grey streets of North London, with its saucy-toga-party vibe and its smiling, topless Brazilian and Polish barmaids. But, by 3AM, the pickings are slim – just a few couples who don't seem particularly inclined to put out, and a legion of thirsty blokes, including the cuddly wanker from earlier. Even Vlad appears to have struck out. When I see my new Geordie mate sitting with his chin in his hand, staring disconsolately at the floor, I wonder how happy the swinging lifestyle has really made him. I also wonder whether or not his wife left alone tonight.
As I'm in the changing rooms getting ready to leave at 4AM, a group of five young lads bound in, post-club, excited to be here and ready for action.
"How many birds in there, mate?" asks one.
I don't have the heart to tell him that they're far too late.
"Loads. You'll have a great time."
Communal sex in highly-chlorinated public baths may not be to everyone's taste. But in this age of creeping gentrification and prudery in our once-great capital, where even Boris Johnson is reduced to singing protest songs against big businesses swapping the sleaze of Soho for boutique fro-yo shops, Rio's quirky charm is something to be celebrated.
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