Isabel Berwick: Winter swimming on Hampstead Heath

It’s a grey winter weekday and I’m on Hampstead Heath, drinking a flask of hot tea while gazing at a huge, iced-over pond. The resident ducks are standing on the ice, fluffed up against the cold. The only sound is the distant hum of London. 

Then comes women’s laughter — and gasps — as they lower themselves into the tiny patch of open water. The lifeguard notice tells us it is 1.5C: “Please shorten your swim”. And at this temperature, a brief immersion is all that the body can bear. When swimmers emerge, their skin is prawn-pink, as though they have spent a couple of hours on a Spanish beach rather than a couple of minutes in a London lake. 

This is Kenwood Ladies’ Pond, dedicated to women-only swimming since 1926. It even remained open during the war — by special decree, lidos and open-air pools remained in use. Older regulars remember the refugee women from that era, many of them German Jews, who continued to swim here for decades after the end of the war.

The City of London, guardian of the Heath, manages this and the nearby Men’s Pond. They are the only lifeguarded open-water swimming places in the UK that are open every day of the year. A third pond, for mixed swimming, is open to the public in the warmer months. 

As a novice winter swimmer, today’s 1.5C dip was the coldest I’ve yet experienced: once in the water, I heard the gentle cracking of the ice around me. I wrote down how it felt as soon as I got out: “A short, sharp, crazy-heightened moment.” As my children say when I tell them about my swims (so far I’ve been up to the pond in rain, ice and freezing winds): “WTF? You’re mad.”

A dip in freezing water may sound an unappealing, possibly mad prospect but it is having a moment. Membership of the UK’s Outdoor Swimming Society has grown by 30 per cent a year since it was founded in 2006, and now has 25,000 members. Wild swimming — in lakes, rivers and the sea — has become a year-round lifestyle embraced by thousands and has generated a mini-boom in businesses and events. Outdoor Swimmer magazine runs extensive listings of competitive outdoor swim events around the world, as well as ads for dedicated open water holidays and neoprene suits. Rather more sedately, a group of Kenwood regulars collaborated on Wild Swimming Walks, a book chronicling enticing day trips within reach of London by train. 

Everyone has their own reasons for enjoying wild swimming but taking a dip far away from the chlorinated regimentation of a crowded public pool or lido is one of its essential pleasures. Wild swimming, one might even venture, is a sensible response to the pressures of modern life, especially the isolating effects of life online. Immersion in natural pools or the sea can be enjoyed as a solitary activity: a communion with nature and ourselves, but often the real draw is that of being with other like-minded swimmers. 

The Kenwood Ladies’ Pond Association, representing its users, has about 500 active members. Even in the depths of winter, up to 130 women a day come to the pond. Many have been coming here for decades — at least one KLPA member is in her nineties. The regulars are delighted at its growing popularity (a busy pond is a viable one, after all) and always happy to share advice and tips.

Mary Cane helped to found the KLPA and has been swimming here since 1982. She started when she was under extreme stress at work and began to run to the pond for a daily 7am swim: “There I found such a friendly group of women. Vera the lifeguard knew everyone it seemed. Such stories and hilarity to start the day with.” Vera would boil up the kettle for cups of hot Marmite, and for bowls of hot water to stand in after a winter swim. “I was hooked!” 

More than three decades later, Mary still swims every day. “When I go away now, the first thing I want to do, need to do, when I return is have a swim in the pond.”

The physical and mental benefits of cold-water swimming seem obvious to those of us who are addicted to it. Explaining them to others can be trickier, because it sounds bad: by shocking the body and triggering the release of stress hormones, acclimatised cold water swimmers are essentially performing a controlled experiment. We force ourselves into a situation where our bodies respond as they would to anxiety or peril. Weirdly, it makes you feel amazing. 

There’s some evidence that by doing this we help ourselves become more resilient to stress. That is certainly my experience. Having spent years learning to manage anxiety, the fearlessness that comes from cold-water swimming has proved a breathtakingly effective way to free myself from its dread grip. 

Aside from the physiological effects, outdoor swimming is also — without being too precious about it — a spiritual awakening. We feel the rain on our faces, notice every detail of the changing seasons. This may be the closest urbanites can come to a moment of real communion with the earth. 

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I didn’t set out to mark my 50th year in such an extreme way. I’ve lived near Hampstead Heath since my early twenties but had visited the Ladies’ Pond only a handful of times. As a picky, paranoid young woman, I found the changing hut primitive, the water dirty and the atmosphere cliquey and unwelcoming. I married, life filled up with children and work. I forgot about the pond. 

Last summer, a friend invited me for an evening swim. The Ladies’ Pond had recently reopened after renovation, she said. She raved about the new “facilities” — the old hut had been replaced by a Scandi-cool changing room, all glass and wood. I’d love it.

She was right. It was a tonic. On hot summer days, the pond can be hellishly crowded — social-media posts have made it far less of a locals’ secret. On a really hot day, there are queues to get in. But on summer evenings I’d swim just before sunset. Often, I’d bump into friends, especially those who grew up here: like generations before them, they started coming here as teenagers. The tradition goes on: my daughter and her friends spend summer days in the idyllic private meadow next to the water (where topless sunbathing has been allowed since 1976 — this is north London, after all). 

The water was at 22C on those heady July evenings. And as high summer turned to autumn, I persuaded my friend Tabitha, a keen swimmer, to come along. She’d been traumatised as a young mother, chased out of the meadow for unwittingly bringing a banned baby inside (no children under eight are allowed). She’d avoided the place for 16 years, and was deeply unsure about returning. 

She loved it. We walked across the Heath for a swim every weekend. We dared ourselves to make it to the end of October. The water temperature drops rapidly as the sun disappears and the leaves fall. Everyone had to decamp to the mixed pond while the ladies’ pond had its annual maintenance check. It was a challenge. The showers at the mixed pond are cold, the changing rooms ancient and open to the weather. The water was down to 12C and our hands were cold for hours afterwards. 

We met one lady who had been coming to the mixed pond all summer, having refused to return to the ladies’ after its renovation. We realised then that much precious history and culture had been lost with the removal of the old huts early in 2016. 

In particularly freezing air one’s exposed skin pricks and stings — it feels as though an army of tiny ants is attacking

Before they were demolished, the swimmers made a short film, Winter Nymphs, named after a 1931 British Pathé newsreel about the women of the pond. Those 1930s women play leapfrog after towelling themselves dry outside. They exude, even at 86 years’ distance, pure joy. Watching the two films back-to-back, I was tearfully overwhelmed by a sense of communality with those long-dead sister swimmers. 

While I loved the female camaraderie, I was also addicted to the swimming. With the temperature now below 12C, we had to make a decision: acclimatise or quit. The body has to be exposed repeatedly to cold water to be able to swim safely, and novices should immerse themselves at least once a week throughout the winter. This transition was made easier — and far safer — because the pond’s all-female team of lifeguards keeps a kind, vigilant eye on every swimmer. 

We vowed to make it to Christmas. As the working weeks rolled by, I looked forward to the weekend, and our walk and swim. Tabitha kept my resolve strong on those freezing, wet days when being outside — let alone stripping down and getting into a lake — seemed like a mad idea. 

So when we sat by the pond early on Christmas morning, surrounded by other women who had slipped away from the heavy burdens of motherhood and grandmotherhood on that busy day, we knew we would carry on. “We’ve done something amazing,” said Tabitha, and we toasted ourselves with the mulled wine that had replaced our usual flask of tea. 

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When I lower myself into extremely cold water, for the first few strokes there is a sense of extreme discomfort. I gasp a bit. We swim in ordinary bathing costumes (some wear bikinis), and pull on neoprene gloves and socks for insulation. In particularly freezing air one’s exposed skin pricks and stings — it feels as though an army of tiny ants is attacking. 

Then I ease into the swim and, even on the coldest day, feel in harmony with the ducks bobbing past, noticing how the light falls on the water, and whether or not the resident heron is standing on the bank. I’m yet to spot the kingfisher that others often see. The only noise is the soft lap of the waves I make, and perhaps the gentle splash of one or two other swimmers. 

Around the halfway mark in my stately single-turn of the pond, something odd happens. My body heats up from within, starting in the chest. It is a feeling like nothing else. The first time I felt it, I rushed out of the water, thinking it was a heart attack. “That’s nothing to worry about,” said one of the phlegmatic regulars, bemused by my panic. “That’s what we call ‘the burn’. It’s the whole point of this.” By the time I heave myself up the ladder I am very pink, (temporarily) warmed through — and euphoric. 

Now, as the spring flowers poke up, Tabitha and I feel we have earned our place in the world beyond the famously forbidding sign on the gate: “Women only. Men not allowed beyond this point”. It is a place apart from modern life and somehow outside time, imprinted instead with the memory of the countless strong, fearless women who have loved the pond before us. 

Isabel Berwick is assistant features editor on FT Comment

Photographs: Walter Bellamy/London Express/Getty; Sarah Saunders