“It didn’t feel like five today,” says a swimmer as he enters the sauna, his skin a livid shade of red, his face so rigid with cold he is speaking out of the side of his mouth. Along with the rest of us, he has retreated into the warmth after a dip in an outdoor pool where the water is indeed an inclement five degrees Celsius (41 degrees Fahrenheit). “Could you shut the door?” a chorus replies. “It’s a cold five,” says a woman sitting in the corner. “I’d say it’s a warm 4.9,” counters a man who is doing squats and lunges. “Yesterday, it felt more like 5.5.”

It is 9:15 a.m. on a January morning, and this kind of granular discussion is standard. There are about 20 swimmers here—a hodgepodge of different ages, shapes, sizes, professions, and personalities, squashed up against one another, some still defrosting, some glistening with heat. All the usual British social barriers—awkwardness, fear of bodily contact, snobbery—have melted away. We are united by our obsession with cold-water swimming. And we are not alone.

Parliament Hill Lido.

In the past few years, the popularity of winter swimming has exploded in the U.K., thanks to “the Wim Hof Method” (the motivational speaker, extreme athlete, and cold-water-immersion expert known as “The Iceman”) and myriad documentaries and articles on the benefits of cold-water immersion on physical and mental well-being. But that isn’t the only reason. The U.K. has a remarkable number of supervised outdoor-swimming spots which make this kind of crazy behavior possible, even in the heart of the capital. However, it is only recently that these pools are being used all year round.

I swim at Parliament Hill Lido, a magisterial, 197-foot, open-air swimming pool in North London. Unheated, and open 365 days a year, the Lido, a listed 1938 Art Deco building, is one of more than 100 such outdoor pools in the U.K., of which 17 are in London itself. Our Lido has its own sauna too, which has rapidly become a nexus for the community of swimmers who come in the colder months.

The original meaning of “lido” comes from the Latin for “shore,” and correct pronunciation is crucial. As the expression goes, “If your dog is called Fido, you say Ly-do; if it’s called Guido, you say Lee-do.” Those who prefer the latter, Italian pronunciation risk sounding “a bit posh,” which in British terms is both good and bad, and too complex to go into here.

I have been swimming through the winter for three years now, and while I am completely addicted, I still feel a sense of dread beforehand. Once in the water, I don’t know if I am cold or hot, such is the burn. Heart pounding, there is no option but to swim, and swim fast, but the sensation is strange—at this temperature, the water feels like molasses.

Cold-water fashion.

Most people who swim here in winter shun full-length neoprene—there is a tacit snobbery about those who succumb. Neoprene gloves and socks—a funny sight, especially when paired with a woolly hat—are acceptable, however. After three lengths, I can no longer feel my extremities, and I haul myself out and head straight into the sauna.

Once in the water, I don’t know if I am cold or hot, such is the burn.

Despite a handwritten sign on the wall reminding sauna-goers to keep the volume down, the euphoric post-swim chatter in this small wooden box can at times be deafening.

“How many lengths did you do today?”


“That is insane. I only managed two.”

“It’s getting warmer this week.”

“Oh, that’s a shame.”

“Did you ever get that sauna installed at home?”

“No, but we did get one in the country house.”

I let it all wash over me, relishing the dwindling cold-water high as my body thaws at a deliciously accelerated rate. This is by far the best moment of the day, and we all know it.

You don’t have to book a pool time in the winter, and while there are limited sauna tickets—$4 per hour—many choose to forgo this in the belief it shortens the high. Between seven a.m. and eight a.m., when the water is still inky-dark and the sauna cocoon-like, the clientele is often a mix of doctors, nurses, and midwives pre- or post-shift. Between 8 a.m. and 9 a.m., it’s the white-collar lot, while between 9 a.m. and 10 a.m. it’s those in creative professions who don’t have to be at their desk first thing in the morning. After 10 a.m. you get the actors, opera singers, and moms—members of a group called Mamma Swim—who guard one another’s infants so they can take turns dipping. If you’re lucky you might even spy the man who reads Shakespeare sonnets to himself by the light of his head torch in the crepuscular sauna half-light.

It’s warmer in than out.

It was only about five years ago that demand for winter swimming was so low that the Lido didn’t bother to staff the turnstiles, and the few mad souls who wandered in at that time of year used to simply slip the lifeguard some coins. Back then, I knew only one winter swimmer, my friend’s mother, who wore rubber kitchen gloves, tied at the wrist, to keep her hands warm. Along with a group of fearless women of a certain age, she remains a lifelong regular at the Hampstead Ladies’ Pond—one of three glorious, lifeguarded natural bodies of water on Hampstead Heath, an expanse of 800 acres of parkland—against which the Lido borders.

But over the past couple of years, the demand for year-round season tickets for the Lido and the ponds—$285, if you want a pass for both—has soared. It is now no longer purely the preserve of the middle-aged. Twentysomethings and even teens are also keen to experience this natural high.

It hasn’t all been plain sailing. There have been an increasing number of hypothermic cases at the Lido; a potent reminder of the hazards of dicing with such low temperatures. The Times of London ran an article entitled No one’s impressed by your hypothermia and questioned why people who say their main exercise is swimming are “always fat.” This encouraged a further backlash against smug winter swimmers, striding around with their fleece-lined “dryrobes”—big, thick towel-like coats—getting chubbier by the day. We laughed it off. They are clearly just jealous of our stiff resolve. In these temperatures, “stiff ” is the operative word.

A great way of breaking the ice.

But are there actually any significant dangers to this daredevil sport? A recent report in The Guardian warned of the dangers of “swimming-induced pulmonary oedema” for those who cold-water swim in the sea, a life-threatening condition that causes breathing difficulties, coughing, and blood-stained spittle.

The Times of London ran an article entitled NO ONE IS IMPRESSED BY YOUR HYPOTHERMIA.

After the article came out, it was briefly discussed in the sauna, and then dismissed. The Lido is not the sea, and, anyway, we aren’t about to stop, are we? Several people I have met say that cold-water swimming has completely replaced a reliance on drugs and alcohol, so addictive and powerful is the high.

Post-sauna, we congregate in the Lido’s café for coffee and excellent cake. I chat with a couple of Frenchwomen, who have been winter swimming for three years and who tell me that their family “nous prennent pour des fous” (think we are crazy), and that no one in France does it. “A few people by the sea. But in Paris, no one.”

Alessio Gorgonio, the café’s barista from Naples, joins in. “It is not part of my culture. Until I came here, I had no idea it existed.” What does he think of the constant stream of teeth-chattering swimmers demanding flat white coffees at the till? “The people who do it, they feel special. They want to talk about it, tell me how many lengths they have done. They are really proud.”

What a smug bunch we are. But perhaps as a nation we are just evolving to be closer to our cooler Nordic siblings - they have been at it for years. Is the next step going naked? I’m not sure we’re ready for that. And what if we are getting fatter? If we are, then it is definitely “brown fat,” the good healthy stuff of sea mammals. And who cares anyway, when it feels this good?

Rebecca Rose is the editor of FT Globetrotter, the Financial Times’s digital city guides