The 8 questions winter swimmers ask about cold

Kate Rew and the OSS team answer the questions new winter swimmers most commonly ask

© Vivienne Rickman Poole

There is an explosion of interest in winter swimming at the moment with The Outdoor Swimming Society’s virtual winter swimming club, Zeno’s, set to have a big second year.  

With so many new winter swimmers stoically dipping their toes into the waterways of the Northern Hemisphere, members of the OSS team involved in local wild swim groups and running our social media platforms are getting a lot of questions – specifically, a lot of these eight questions. Here, we answer them in one place – with links where relevant to more in-depth advice pieces in the OSS Survival Library.  

DISCLAIMER: Own every decision you make: risks of entering very cold water include heart attack, asthma attack, panic attacks, cold incapacitation, cold shock, drowning, hypothermia and death. With the freedom to swim outdoors comes the responsibility to do it safely. The OSS is a peer-to-peer community that shares experience between individuals, but neither The OSS nor any of our agents are responsible for swimmers’ decisions or the accuracy of any information given. Understand more on the risks including high blood pressure  and cold incapacitation

1. What does it feel like?

Do not let images of smiling girls in bobble hats and bikinis and fashionable chat about ‘the cold water cure’ deceive you: winter swimming is, as Lewis Pugh puts it, ‘a violent physical assault’ on the body. With its immediate effect on blood pressure it is literally not for the fainthearted. 

Cold water will punch the air out of your lungs, it will bite your hands and feet off. After a minute or two I generally have the sensation of a giant lobster clamped to my buttocks. 

Cold drives the sense out of you. On a very short solo swim across Bowscale Tarn I became convinced the rock opposite was magnetic, and was repelling me. I turned around to go back and then realised it wasn’t some otherworldly force on the far bank, my arms had grown weak already (and clearly my rational powers also – this is ‘cold incapacitation’ as I now know it). 

Cold water will leave you shaking coffee all over yourself, unable to do up your own bra strap. It will leave you sitting on a car park floor in a north wind with your wetsuit stuck round your ankles and your hands too cold to do anything about it. Just sat there in your own puddle, with what feels like a real choice between saving yourself and giving in to a weep.  

Swim Envoy @swimstaman is a more experienced distance winter swimmer, and goes in with and without a wetsuit. He likes the “immediate thrust into the present moment. Are you dying? Can you cope? Could you die? Most of these things cross my mind. Usually around the turn from Autumn to Winter I typically have a ‘bad’ swim with such pain in my hands I think I’m permanently damaged. Once I couldn’t use the key to get into my flat. A couple of years ago I ran laps of our small city flat actually crying in pain. Be prepared!”

So. Great that you want to join us, but know (see disclaimer) that cold water can lead you to hospital. Please go slowly and carefully if it’s a journey you want to take, and consult your doctor if you have any reservations, and particularly if you have high blood pressure, heart disease, asthma or any condition that might raise your own risks. 

2. If it’s x degrees, how long can I stay in for?

Once upon a time, somebody, somewhere, said something like ‘you can stay in one minute per degree – above 10 degrees.’ This has gone through the urban myth wrangle and come out as a broken (rule of) thumb: ‘double the degrees C to get time in the water’ (no mention of the 10 degree boundary) and ‘you can swim twice as many lengths as the water is degrees’ (no! Don’t do that). All of these answers are wrong, perhaps dangerously so.

There is no universal answer to how long you can stay in for, it depends on your body. Start out with small dips, see how you are after you get out, extend your time in the water gradually and make the journey into cold your own personal experiment. You will find there is not even any reliable answer to ‘how long can I stay in?’: how much cold an individual body can take will vary from day to day, depending on sleep, health, hangovers, stress, recent acclimatisation, what’s been eaten and time of day.

Go carefully, and don’t be a sheep: what someone else is capable of is not a guide of anything when it comes to you. The chit-chat on winter swimming is often about how you feel alive because you didn’t die. That it’s perishing, but you didn’t perish. Something to remember is that you could: Ice Milers spend 20-60 minutes in under 5 degrees water to accomplish their feat, a length of time that is generally associated with data on ‘survival rates’, unconsciousness and death. Back at the start of my winter swimming it was a revelation to me when a lifelong winter swimmer at Battery Rocks in Penzance shared with me that over winter she counted strokes, not minutes – 10 or 20 strokes being her winter challenge (the sea was 6 degrees). This reset my expectations: at very low temperatures a minute or two may well be long enough (if it’s acceptable to your body at all). 

The question about ‘how long can I swim?’ is really a question where the ‘edge’ is for you – the edge between a swim being safe or risky, being pointless or worthwhile, being enjoyable or bad. Do you want to cold swim, then go on with your day – or is the physiological switch you’re flicking only available to you if you get so cold it stays with you for hours afterwards? Years ago I observed to a Tooting Bec swimmer that what put me off winter swimming was that I felt sleepy all morning afterwards. ‘Oh yes,’ he observed ‘we all do’. Not everybody wants that at work.

  • See ‘How Cold Water Feels’ for more information on bands of temperature and how they’re experienced. 
© Natasha Brooks

3. What’s the best way to enter the water – slowly or just jump in?

The best way to enter water is slowly, in a controlled way. One of the first things you will learn to control as a winter swimmer is the ‘gasp’ reflex, where it feels as if the cold water has punched the air out of your lungs, and you cannot breathe. If this happens to you: exhale with a strong ‘fwaw’. This may feel counterintuitive but if you puff the air out the next breath will come back in. Then concentrate on steading your breathing rate and taking a few steady head up breaststrokes. Stay in the shallows until you can control your breath so that, if need be, you can stand up or walk back out.

Being asthmatic increases the risks of winter swimming, but some people do swim. Beth Pearson, OSS elsewhere editor, is one of them. ‘If you’re asthmatic, there’s an additional psychological barrier to get through, as the feeling of tightness in the chest is one you associate with having an asthma attack. For me this means I spend longest acclimatising my chest, regulating my breathing and having a word with myself!’.

Cold sensitive people tend to have a more pronounced gasp reflex, says Professor Mike Tipton, from the Extreme Environments Laboratory at the University of Portsmouth. I would put myself firmly in this category. My preference is to dab water on myself before I get my body in. I put my hands in the water and then put the cold water on my cheeks and face, the back of my neck and my pulse points – inside of wrists and elbows. I do this a few times till I feel ready to get in. For me this helps mute the shock of the water. 

4. What’s the best way to warm up afterwards?/ What is afterdrop and how do I stop it?

Thermal regulation is so important to the vital organs that the thermo-regulatory system trumps others (such as hydration levels) to maintain a thin band of survivable body temperatures. The first thing that your body does when entering cold water is to start to shut down blood to the skin to conserve heat. The skin and fatty layer then become an insulating buffer zone to protect the core – your very own ‘bioprene’. The thicker the layer of fat, the better the insulation it provides. ‘Cold diuresis’ occurs as this happens – you generate a lot of pee. Over time blood may also leach out of the muscles, this is how ‘cold incapacitation’ occurs in a swimmer: their muscles become incapacitated by cold, making strong swimmers weak.

When you get out from a swim, this process reverses: blood returns to the skin, and cools down in the process. This is why you will be at your coldest 10 minutes after you get out.

The best way to see yourself through ‘afterdrop’, is to change immediately. Dry yourself off (pat, don’t rub), add lots of warm layers, and have a warm drink. Put yourself in a warm place. See The Subtle Art of Warming Up for more tips. And don’t drive until you feel well. 

5. Do I need to acclimatise?

‘Acclimatisation’ is the process whereby the body is able to deal with longer periods of cold water without suffering (overmuch).

Marathon swimmers such as Lynne Cox, and people with goals about distance and endurance, recommend swimming outdoors at least once a week, and making the cold a way of life – wearing lighter clothing, having colder showers, training in cooler pools.

Social winter swimmers (who like to get together a few times a week or month) cite the benefits of carrying on swimming from summer to autumn so temperatures are experienced and acclimatised to as they drop (rather than in one go).

But stunt winter swimmers will just get in once or twice a year – a dash and dip. The risks of this are higher but if you are otherwise healthy, it is perfectly possible to just do a few winter dips a year with no acclimatisation, in the style of many festive swimmers (see ‘Festive Swims Dos and Don’ts for more information on the risks of this approach).

6. Do I need booties, gloves & hat?

Winter swimmers vary widely in what they wear – from thermal wetsuits and neoprene accessories to bobble hats and swimming costumes. Neoprene booties and gloves are effective in reducing pain to the hands and feet of very cold water.

Head gear (whether bobble hat or neoprene bonnet and swim hat) can help with warmth. Submerged in very cold water in a swimsuit, with wind and rain whipping through your hair, the old wives that 50% of heat is lost through your head is closer to being true than ever. The body can achieve a 99% reduction in blood flow to the skin between the extremes of vasodilation (up to 6 litres of blood to skin per minute) and vasoconstriction (blood flow down to 0.02 litres per minute). The only place this does not occur is the head – blood flow to the scalp remains similar across all conditions. This does not mean your mental function is unimpaired – one of the dangers of winter swimming is hypothermia and bad decision-making. 

Cold water in the ears can affect balance – some use ear plugs to reduce dizziness. (You can also do head up breaststroke). 

7. Where is it safe to swim in winter?

In swimming there is no such thing as ‘safe’ per se, there is only ‘safe for you’. The sea tends to stay warmer than rivers or lakes, rarely dropping below 6 degrees, but can be prone to winter sea storms and more challenging (that is, dangerous) waves and currents (plus: no lifeguards). Winter opening lidos offer controlled environments with shallow ends to experiment in. UK Wild Swim Groups may offer others to swim with – though that doesn’t take away the need to be responsible for your own safety. 

Please remember that “safety” is not an absolute with swimming – it varies with factors such as rainfall, temperature and ability. A location with few risk factors one day may have many at another time: for example a slow flowing river in summer can become a raging torrent of floodwater in winter. And it depends very much on the person who is going to swim, their capabilities, experience, strength and so on. So it’s best to assess the risks at every place on every visit, and each swimmer to assess in relation to themselves.

Some places do have features that are more likely to make a swim safe for more people, such as shallow beach entry and exit points, slow or no current.

8. Why do it?

Within the OSS team people love winter swimming for all the philosophical, physical, social and physiological reasons there out there. 

‘I do it because I can,’ says @swimstaman, who lives by the lake in Zurich. ‘ I do it when I think I’m going to explode. I do it when I’m feeling a bit ill. I started doing it regularly after my dad died, and it sort of became the only thing that helped. To be honest it’s become a bit of an addiction. This year, I didn’t want to do it, but I knew it would improve my mood, so I carried on. Some days I think I should be able to control my temperament more easily, without throwing myself into freezing water but, I live by a lake and ‘whatever works!’

I do it as an exercise in stoicism, a practise in ‘not minding’. I do it as a mini-adventure in a pretty domestic life (I have two under 10s). A day when I fit in a freeze or a run before school drop off is a good one. (As Robert Macfarlane put it, ‘discomfort has become its own luxury.’).

So whether you do it to just to keep swimming, to keep up with swim friends, or for the the physiological and psychological changes you feel it induces (an increase in happiness perhaps, a reduction in anxiety): enjoy. And swim safe. 

See also