The snow-covered surface of an icy loch, for some is just an invitation to get out the sledgehammer, hack away and plunge in. When Vicky Allan and photographer Anna Deacon, cold water lovers themselves, started to research their book on the health benefits of wild swimming, it was the ice swimmers that lured them most

THE field of snow covering Uath Lochan in Glen Feshie gleamed in the winter sun. I remember wondering, as we approached its pristine expanse, how thick the ice under that blanket might be. Would it be centimetres deep, too hard to crack open with a foot? Or thin enough to break by hand? Fortunately smashing into it would not be a problem, for one of our companions had, slung over her shoulder, the sledgehammer which she keeps in her car boot at all times during the winter, for precisely such moments. It's not for nothing that Alice Goodridge is nicknamed Alice "the hammer".

“I don’t feel like my place is to destroy the beautiful ice, it’s just to create a small entry,” she reassured us, as she and her friend, Sarah Wiseman, tested the loch’s icy shoreline. “Just a small area so I can get in and have a little dunk. I feel addicted to the cold. I get excited by the thought of getting in that cold water when I see it. That’s one of the ways my feelings about swimming have changed. Because I never used to be dying to get into the ice.”

This was just my second ice swim – my collaborator and photographer Anna Deacon’s fourth or fifth – and I felt the churn of butterflies as we stood at the edge of the loch. One of the reasons we were here in the Cairngorms was to experience swimming in properly cold water, far more chilling than the 5C of the North Sea off Portobello which was where we regularly swam, at, on this occasion, 0.4C. We were also planning a book, which would be titled Taking The Plunge, and looking for stories from people for whom submersion in cold water was all about relief from physical or mental health problems.

What I found fascinating about the ice swimmers is how much, like me, they almost love the cold. In midwinter, as the temperatures plummet towards zero, these swimmers would choose to ditch their wetsuits, worn over the summer for endurance training, in favour of bathing suits. When the temperatures rise in spring, extraordinary as this may seem, they would fret. Their beloved cold, and all that it gives them, is leaving.

“Alice the Hammer” was just one of these cold-obsessives. In the last year she set up the first ever Scottish Winter Swimming championships as part of her mission to bring together the community of what some people call “shiveries”. She also runs Swim Wild, which organises wild swimming events and tours.“I’ve always been fairly good with the cold,” she told me. “The difference is that I now feel addicted to it. I get excited by the thought of getting in that cold water. Then that completely goes away for a few minutes and I’m actually getting in it and I’m like, ‘Oh my god what am I doing this for?’ Nowadays I get a, ‘I really need to get in’ kind of feeling. That’s new. Because I never used to be dying to get into the ice.”

Wearing no more than a star-spangled swimming costume, woolly hat and neoprene gloves and boots, she stepped up to the lochan edge. With one foot she prodded the ice, which did gave way. It turned out it was fairly easily breakable. She quickly began smashing at it with hands and feet and formed an entry hole there at the edge, a murky brown portal in the shimmering ice. Goodridge lowered herself slowly into it. As she did so, she sung out a long, high choral note – as if channelling the heavens or some other-worldly pain.

For a moment, Goodridge hesitated there, thoughtfully. “Rooty. Squelchy,” she said. There was no mention of the temperature. A robin hopped between the trees – a casual onlooker. “I don’t know what I’m standing on – some kind of platform," she said. "I’m going to stand on this platform to smash a bit of ice.” The water she stood in, dark and peaty, was black as night. Impossible to see what lay beneath. Seconds later she was lunging forwards with an Olympian hurl of the sledgehammer, walloping down onto the surface ahead of her. Ice fractured. As it cracked it sounds like splintering branches. The hammer glugged down into the water, then heaved up and smashed again.

Ice-swimming is not for everyone – and actually one cold physiology expert told me that there are two types of body, those who feel the cold pain, then have a reasonably long phase where they can tolerate, even enjoy being in there before the threat of hypothermia sets in, and those that go from pain to danger zone with nothing in between. Nor is it something anyone should plunge into doing without proper build up and acclimatisation. Every year people drown because of the hyperventilation and stress caused by cold-water shock – usually after they have fallen in the water. Hypothermia is real. If you’re feeling inspired to do any of this, I would advise you get some proper safety advice and do it only in the company of experienced people.

Research, still in its early stages, however is starting to show us that some exposure to the kind of physiological stress caused by these low temperatures may be health-enhancing. Swimmers often rave about the positive effects. “I think it is addictive,” Alice said, “and it’s also beneficial, mentally and physically.”

It was hearing so many stories testifying to these benefits that made us want to write a book. Stories like that of Cairngorm swimmer Karin Mackinnon, who came off opiates and anti-depressants once she started swimming. Or Dawn Craig, who only a few years ago had been unable to walk, but now credited the fact that she was climbing Munros to wild swimming – and was planning go swim the English Channel.

Or Sarah Wiseman, there at Uath Lochan, helping Alice Goodridge crack the ice, who talked about how swimming helped her with both her “generalised anxiety disorder” and also the pain of costochondritis, an inflammation of the connective tissues in the ribs and sternum. “I have a very busy head,” she said. “For me going in to the water clears it all away, and resets that busyness. It’s like a start from scratch, a reset button.”

She was standing in the channel created by Goodridge, further clearing it by throwing aside shards of ice so that they bounced over the white surface. Cold water swimming, she said, wasn’t a cure, but was something that helped. “It definitely,” she added, “puts a full stop in somewhere and gives you a little bit of a break from whatever is going on in your busy brain.”

Why might it be having this effect on mental and physical health? One person who has since given me some possible answers is Mark Harper, a consultant anaesthetist and cold-water swimmer who is part of a team at the University of Portsmouth, driving research into the benefits of cold-water immersion. He is involved in research into both how cold-water swimming might help with depression, but also how it may reduce inflammation and pain. “Cold-water swimming appears,” he told me, after we took a dip together in the North Sea off Portobello, “to be one way of dealing with inflammation, which itself is at the root of a lot of health problems.”

A long-term wild swimmer, he studied perioperative hypothermia and developed an interest in how a programme of cold-water immersions could be used to condition the body to deal better with the stress of surgery. From this, he went on to look at how stimulating the stress response through cold-water swimming might help us deal with stress in other parts of our lives.

As a swimmer, Harper knew that a cold-water dip made him feel good. He’d been aware of that from the very first time he’d ended up in the sea at Brighton after finding his local swimming pool closed. “A friend said to me, ‘You should go swimming in the sea.’ When he told me they swim all year round, I thought, ‘You must be mad.’ But I went and swam round the pier and it was 18C, the warmest time of the year, but I still remember walking up the beach afterwards and thinking, ‘Ooh, this feels good.’ And so, instead of stopping when the pool reopened two weeks later, I just carried on. For 15 years to date. What I now know is every time I go for a swim, no matter how bad I feel when I go into the water, I always feel better when I get out.”

Part of the problem today, Harper says, is that almost all of us experience low-level chronic stress, rather than intermittent big stress. “We used to be worried about running from sabre-toothed tigers, now it’s running to get to a train on time. That low-level stress can be reduced. You can do it by adapting to cold water, which means you then cross-adapt to other stress.”

As he points out, we only have one physiological system to deal with stress – rather than different responses for each stress – and that is controlled by our autonomic nervous system, the control network for our body’s unconscious functions. A tight deadline, for instance, triggers an analogous response in that same system as the sight of a sabre-toothed tiger. “This means that if someone swims in cold water regularly,” he says, “we can expect them to reduce their response to a different stress – to any stress – like the low-level one of running for the train.”

A key body mechanism thought to be involved in the positive impacts on inflammation and depression, is what’s called the “diving reflex”. It’s what happens when you put your face in cold water and trigger a huge stimulation of both parts of your autonomic nervous system which controls your unconscious body processes – the parasympathetic and sympathetic branches. Messages are sent out through the parasympathetic nervous system that put your organs into “rest and digest” mode, lowering heart-rate and reducing inflammation. But also, at the same time the chemicals, serotonin and noradrenaline are released, and it’s believed that these turn on the pain-inhibiting pathways in the brain.

This, I soon realised was why many people in the swimming community were talking about stimulating their vagus nerve in the brain – why there was all the talk of cold showers, and “getting your head under”.

Cold-water therapy, of course, isn’t a new idea – but it’s perhaps something that’s been lost or has fallen out of fashion. Back in the 18th century, sea swimming, especially during winter, was recommended for the treatment of a range of diseases. Whole seaside resorts were founded on these perceived health benefits. The Victorian era Scottish hydropathic institutions that sprang up were partly about "the cold water cure". In some ways this isn’t some new craze, but going back to an old one.

While ice swimmers will talk about the zing they feel afterwards, they are also often honest, and appreciative of the discomfort the extreme cold causes. These days, some will tell you, we humans have got good at surrounding ourselves with creature comforts. The environments we’ve created, at least in the developed world, revolve around heated car seats, air-conditioned malls, duvet jackets, hand warmers, rooms that are neither too hot nor too cold, comfort food. But ice swimming is the opposite of comfortable.

The idea that getting out of our comfort zone in the extreme cold is good for us, even healing, is one that has been gaining traction in recent years. One person who has done more than anyone to popularise it is Wim Hof, the Dutch endurance athlete known as the Ice Man. Using his own invented breathing and training system, Hof has climbed up Everest and Kilimanjaro in nothing but his shorts and shoes, and he holds 26 Guinness World Records, including one for swimming under ice. He even seems to be able to control his immune system. The claims Hof makes about his method seem outrageous – that it can help counter autoimmune disease, arthritis, depression, autism – but he is developing an ever-increasing following. Whatever it is Hof has, plenty of people want it.

One of Hof’s messages is that modern life isn’t good for us – for our brains or our bodies. In our comfortable, heated, air-conditioned worlds we are “de-stimulated”. We are not exposed to the kind of environment for which our physiology is built.

The Wim Hof Method is partly spread through certified instructors. One of these is Allan Brownlie, who runs courses, workshops and retreats in Scotland and further afield, with whom I did a course in the summer. “I always tell people,” he said, “that you have the comfort zone, and then you have the non-comfort zone. Then if you really push it further you go into that danger zone. Sometimes when you have a good understanding of what the cold can do to you, it is good to go into the danger zone. I’ve done that.”

Brownlie believes that this “non-comfort zone” is important. “When something gets uncomfortable you learn something. You learn that pain is only temporary. You can relate that to anything. Being uncomfortable emotionally is a bit painful. The non-comfort zone is probably at certain stages the learning zone, where you progress. What you want is definitely not always to be in the comfort zone.”

Through his Wim Hof courses, Brownlie has taught Hof's breathing method and introduced many people to cold water immersion. Of course, you don’t need the Wim Hof Method to be able to get into cold water. Most of us do so without the help of his breathing strategies and have found their own way of tackling it. Most people aren’t there because they’ve read or heard of Hof. They’re there because somehow, at some point, they decided to throw themselves at a chilly body of water and found that it was a bracing, invigorating thrill – and one that left them feeling lifted for hours afterwards.

When I lowered myself into the ice hole at Uath Lochan, wearing nothing but a swimsuit and neoprene gloves and socks, I didn’t perform any special breathing. I had barely even heard of Hof. Nor was I really coming to it hoping for it to provide healing or relief. I came to it for the thrill, for the journey of different sensations. This was coldest water I’d been in yet, and I was nervous. I was probably expecting a bigger shock than I experienced. It strikes me that once you get beyond a particular level of coldness, the shock is just the same. It’s cold, yes, but all you really know is the shock your body is feeling. A cold that almost burns into you, that makes you feel as if you are yourself a prickling hot coal. Your body screams, but it isn’t exactly pain. Your whole attention is being drawn to what’s happening to every part of your body. Then suddenly you realise you feel fine, you feel great, and this lochan you are in is so stunningly beautiful, and all you can do is take that in. And part of what I love about it is that all this happens – this big physical journey towards a kind of mindfulness – in a matter of minutes.

Taking The Plunge: The Healing Power of Wild Swimming for Mind, Body & Soul by Vicky Allan and Anna Deacon is published on November 7