Why Winter Is the Best Time to Dive Into Wild Swimming

Plunging into your local lake or river shouldn’t just be a fair-weather pursuit. Taking the plunge in winter waters promises a host of bracing health benefits

By: Jamie Millar

Man swimming in a lake

Evolved from fish, humans don’t let the fact that we’re very much land animals stop us going back to our old habitat, maladapted as we now are. The tension is part of the draw. 

“We are pulled to the paradox of water as a source of life or death,” writes author Bonnie Tsui in her book Why We Swim. Once there, “we find ourselves flexing our survival muscles, achieving something quietly triumphant with our persistence in the medium”.

That partly explains the wild popularity of wild swimming, which by its free-range nature is hard to quantify. But Outdoor Swimmer magazine’s first annual trend report, published in February, estimates that since 2019, participation in outdoor swimming (wild and otherwise) has increased between one-and-a-half and three times. Anecdotal evidence also suggests a surge. A new swimming club close to where Outdoor Swimmer founder and publisher Simon Griffiths swims in the Thames two to four times a week has attracted 400 members in a year: “And this is people who are swimming all through the winter in a murky, cold river.”

It sounds, well, wild. But in his book The Other Side of Happiness, University of Melbourne social psychologist Dr Brock Bastian explains the concept of “benign masochism”. Overcoming a perceived threat results in a “hedonic reversal” of negative experience into positive. And relief of a negative experience is itself a positive that increases your pleasure more than if you’d never felt discomfort.

You adapt to repeated experiences positive and negative – but not to the “opponent process”, so over time the pleasure of relief can rise even though the pain of getting into cold water subsides. That also releases painkilling opioids and dopamine, neurotransmitters involved in liking and wanting – and the “runner’s high”. Hence why wild swimming addicts say they need their “fix”.

Another explanation for the pick-up in wild swimming is, says Griffiths, “the turbo-charge effect” of lockdown. Initially, wild swimming wasn’t a government-mandated form of exercis – and besides, it was March last year. Cold. But in May 2020, Boris Johnson expressly permitted “open-water swimming” with one other socially distanced person.

That coincided with warmer weather and released pent-up demand, some from pool-goers desperate to swim anywhere. Between 2019 and 2020, Google searches for “wild swimming” increased by 94 per cent; popular spots were deluged. And Griffiths thinks numbers didn’t dip when indoor pools reopened in July 2020 and through winter: “So many people are realising that swimming outdoors, and the whole lifestyle that comes with it, can really help with your mental health and general sense of wellbeing.”

As Tsui documents in Why We Swim, faith in the salubrious properties of cold water dates back at least as far as Ancient Greek tragedian Euripides, who believed that “the sea restores men’s health” – and that it cured his rabies. In the mid-eighteenth century, Benjamin Franklin swam in the Thames daily, reflecting a fashion for taking the “water cure” that precipitated the founding of the English seaside resort and the establishment, by the outbreak of the American Civil War, of 200 dedicated clinics across the pond for everything from broken bones to typhus, fever to nosebleeds. “Proponents didn’t know exactly what they were talking about when it came to why,” she writes. “But they knew what felt good.”

While modern science has poured cold water on some claims, latter-day wild swimming converts are evangelical about miraculous-sounding benefits. According to one article in the Guardian, wild swimming can cure a broken heart. According to many other articles about wild swimming in the Guardian, it can also fix almost everything else that ails you.

Science does back the claims up, though; a study published in British Medical Journal Case Reports found it can be a treatment for major depressive disorder and anxiety. A 24-year-old woman who’d been treated for the condition since 17 was able to cease her medication after four months of weekly open-water swimming. She told researchers the effect of the cold water was “like a weight being lifted off my shoulders”.

Woman in swimming costume with Huel

“This is not made up,” says Mike Tipton, a professor of human and applied physiology in the University of Portsmouth’s extreme environments laboratory, who co-authored the study. “It’s just I can’t tell you how it happens.”

Certainly, says Professor Tipton, the flood of stress hormones released when you drop a tropical animal into cold water – 15°C or below – will, as wild swimmers attest, make you more alert. But as for the wilder claims of reduced depression or improved immune function, “the definitive experiments just haven’t been done”.

It’s hard to separate the proposed physical and mental benefits of cold-water immersion from the well-proven ones of exercise. Or “green therapy”: time in verdant natural environments is linked to lower depression, stress and anxiety. Or “blue therapy”: being in or around bodies of water is associated with feeling less blue. Or the social aspect: because if you’re sensible, says Professor Tipton, you’re going to go wild swimming with somebody else.

Wild swimming’s social aspect is key, says Griffiths – especially in winter, when you can only stay in the water for ten minutes. After the shared, challenging experience of the sort that’s proven to enhance bonding (strangers with nothing in common except being electrically shocked in a research lab like each other more), you quickly get dressed, have a hot drink, eat some cake, express incredulity that you were all just in that. On the dedicated WhatsApp groups, the stream of chatter is constant. What’s the water temperature? And the flow? Did you see the sunrise? Is it cold enough for gloves? 

Technically you don’t need any kit for wild swimming, says Griffiths. But most people prefer a swimming costume, goggles for eye protection and a cap to trap heat and long hair. Heading into winter, you might want a wetsuit for warmth and a bright tow float for visibility. Connecting with others is “a really, really good idea” before you start wild swimming: “It’s very safe if you know what you’re doing; it’s potentially deadly if you don’t.” 

One of wild swimming’s deadliest hazards is cold-water shock. (Others include fatal arrhythmias, for which there seem to be predisposing factors, and non-freezing cold injury, which is not yet fully understood but can be debilitating and permanent.) Just your first involuntary gasp on immersion can, says Professor Tipton, suck in enough water to initiate drowning. That’s why going into cold water slowly, which minimises the “inappropriate” fight-or-flight response, is better. And why once you’re in, hey, it’s not that bad!

The danger then is, because your skin receptors habituate, you can become physically incapacitated as your muscles and superficial nerves cool or, worse, slip into hypothermia and unconsciousness – all without feeling cold. Hence Professor Tipton advises limiting cold-water immersion to ten minutes. (Outstaying your welcome is also “probably” detrimental to immunity.)

You’ll be colder still around 15 minutes after getting out, when the “cold front” moving from your skin to your core hits – so don’t be driving home then. Wait until you’ve stopped shivering and your fingers feel warm to your lips. A hot drink won’t make much difference but is “psychologically beneficial”.

Lest that dampen your enthusiasm, Professor Tipton hypothesises that humans as a species have gotten so comfortable that we almost unconsciously pursue extreme sports to restore the “perturbation” needed to keep our bodies functioning properly.

He’s “not a devout open-water swimmer” but he does triathlons and lives in Cornwall, where he bodyboards in the sea – admittedly more in the summer than the winter. Surfers have, he says, long realised the power of untamed water for good physical and mental – dose dependent: “I think it’s probably something that swimmers are now discovering.”

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