It’s a chilly morning in Walpole Bay, Kent, and I’m waist deep in the sea. Unable to stand it any longer, I wade out and sprint across the sandy beach, where – joy! – a wooden sauna is perched on huge rusty wheels. Modelled on a Victorian bathing machine (appropriately enough, as we’re in Margate, one of the UK’s original seaside resorts) this free community sauna is the baby of Dom Bridges, the founder of local skincare brand Haeckels. “I don’t see it as an elitist pastime,” he tells me. “It’s important to provide healthy spaces to congregate, to build community while also focusing on our mental and psychological health. It shouldn’t be something you have to pay for.” Locals agree. Volunteer Rosalind Nelson, who opens up every Sunday, says: “Everyone is always in a brilliant mood, because they’ve just swum, so they’re at their best mentally and physically, and they get to look at this wonderful view and warm up.” One user, Carol, tells me that she’s had breast cancer twice and says it’s helped her recovery; another local, Tindara, says: “It just clears your mind completely.” Although we think of modern-day sauna culture as Scandinavian, it’s actually an ancient British practice, with the oldest archaeological evidence found near Stonehenge, as well as a bronze age sauna on Westray, Orkney. But in Britain, saunas have often been seen as naff add-ons to resorts or leisure centres. Now that’s changing. In the last two years, “at least 50 ‘new wave’ UK saunas are either already up and running or being built, with many more in various stages of planning”, says the British Sauna Society founder Mika Meskanen. This summer’s festivals are setting up wellness areas with saunas, while author Caitlin Moran called the sauna “the new pub”. “It’s a massive movement,” says Heartwood Saunas’ founder Olly Davey, whose construction studio is flat out with commissions. “There are not many beaches around the UK that haven’t got something planned.” Whenever you start talking to enthusiasts, one sauna keeps coming up in conversation: Beach Box, Brighton. I travel there to meet Liz Watson, considered by some to be the “mother” of the new sauna movement. “It just makes us all so happy,” she says, beaming. “Everyone leaves with a smile on their face.” Watson started Beach Box as a pop-up in 2018, part of the Brighton fringe’s Finnish season. “People loved it; we were fully booked.” We’re sitting on high pine benches in her Finnish-style löyly (a Finnish word for the steam that rises from a stove) sauna, with its snug felt ceiling, and stove filled to the brim with volcanic rocks. All wood used is sourced locally from estates in Sussex and the whole enclave oozes DIY charm. Watson bought three horsebox trailers – 2 metres by 3 metres – on eBay, and local builders transformed them into saunas. “But you can use anything,” she says, “from old caravans to sheds and buses.” The heat is gentle but intense. “As you stay in the sauna longer,” Watson says, “it’s a cardiovascular workout: the heat gets deep into tissues, the heat shock proteins get released, the endorphins. It reset my whole life, really.” Aberdeen beach hosts the country’s first mobile sauna, called Haar (“sea fog”). “Scandinavia has always been a big part of our lives, influencing us in almost everything,” says owner Callum Scott. “My main job is a primary school teacher, and the sauna, a side project, helps me switch off.” His sauna has also been converted from a former horsebox, with a larch cladding exterior. “It’s locally sourced, while the trailer roof is painted British racing green.” Deciding to keep costs as low as possible, Scott started the build in a nearby stable yard at evenings and weekends, working seven days a week for months with help from his family. Inside lies an Estonian-made wood-fired stove; the space is kitted out with local Scots pine. Eucalyptus leaves are hung on the walls. Scott wanted to ensure it was portable. “It’s 2 metres by 5 metres, and less than 1.5 tons, so anyone can tow it. I wanted a sauna for the seaside, but also for touring the snowy mountains and coastal towns.” In the six months it’s been open, it’s already travelled across Scotland. It’s now moved on from Aberdeen beach to the Cairngorms national park, where it will remain until November. “I especially love the social aspect,” he says. “It’s a safe space to meet friends in a relaxed atmosphere.” Iend my journey at Hackney Wick community sauna in London, a formerly derelict site behind a 1930s municipal bathing house. It is “authentic, affordable and inclusive”, says co-founder Victoria Maddox, as we sweat in a large 12-person sauna. It was “originally built by a German company for top-end showjumping horses”, she says, “but they didn’t like it.” All the wood and windows were reclaimed, and the sauna rebuilt on to the trailer. They’re keen to reach out to Hackney’s diverse population. “We recently asked a community swim group to come down,” says co-founder and anaesthetist Oguguo Igwe. “I’ve never seen that many Black and Asian people in a sauna, and I was looking around and I was, like … this is amazing.” A brand-new sauna has just arrived, and the team are keen for me to try it. A small space heated to a ferocious 90C, we’re dripping instantly. We wear hats, which “trap a layer of cool air between the head and the heat”, Maddox says, “so it helps to regulate your temperature better.” But still, this is heat on another level. “We call that ‘sauna head’,” she says, glowing. “It makes you go into a slightly meditative state and you lose your edges, your ego dissolves. Time disappears.” Afterwards, we plunge into converted whisky barrels filled with icy water. What about planning permission? In Folkestone, tattooist Tim Smithen has been in talks with the council to install his Steampunk Sauna on Mermaid beach. “I’ve been proposing it since last July,” he admits when we chat the next day. “Everything takes time – but it will happen.” With its unquestionable benefits, this is a movement with a life force of its own. “You come out feeling like you’ve been on holiday, with a sense of space in your mind,” Brighton Box’s Watson tells me. “Sweating has its own release and calms the thoughts in my brain. It’s like sitting in a pub, it liberates you, and you end up having the loveliest chats.” The sauna feels like a level playing field: you meet people from different backgrounds whom you wouldn’t otherwise necessarily encounter. Or, as the society’s Mika Meskanen summed it up: “Communal sauna brings about social cohesion – and puts restless minds at ease.”