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The Colder the Better - But how to Begin ?

Updated: Dec 6, 2023

As we delve further into winter, the outdoor water temperatures within and surrounding rural and city environments fall, yet, the swimming  activity within them does not. If anything, it may actually increase. But why are people doing this, and how do people start ? 

Some love to swim in the open sea, some love to swim in lochs, lakes, or rivers and some frequent lidos. (Photo of a regular visitor to the Outer Hebrides enjoying one of our winter swim yoga retreats.)

If you are reading this, there will be a reason for it. Maybe you are a regular outdoor swimmer, whose eyes widened slightly at the image of cold water swimming, whilst you calculated the hours until your next dip, and recall just how much the day will improve once you are in that cold water. Maybe you are new to outdoor swimming, and want to absorb every piece of information you can possibly find about this phenomenon you are experiencing (this quest does not go away). Or maybe you are yet to dip your toes into anything outside of the bathroom, but are intrigued by the semi - clad people you see immersing themselves in cold water, whilst laughing with joy, and not shrieking in pain.  Why are some of them actually in swimsuits and not neoprene? How on earth did they discover they not only like to do this, but love it, and, if you want to,  how do you take your first steps towards dipping safely into this world? 

“What's the addiction?" I would ask myself as I watched them. "What are you afraid of? Getting swept away in their euphoria? Letting go to welcome something new, old, challenging and nostalgic of youth?"


Cold Water Swimming - More than just a drop in Temperature

Cold water swimming is by no means new, especially within Scandinavian countries,  but the uptake of participation across the British Isles has increased significantly over the past five years. As with any sport, the level at which you participate is determined by many things, but the resounding connection across all cold water swimming disciplines, is the intense expression of wellbeing that swimmers experience.

“It helped me recover from an injury and makes me feel alive!”

Whether they wear wetsuits, sports watches, and log every move on Strava. Or ‘skins’ and a bobble hat for a sociable ‘dook,’ - every person you talk to, will speak positively about how the experience makes them feel. Some love to swim in the open sea, some love to swim in lochs, lakes, or rivers and some frequent lidos. But, all of us not only express how it has improved our sense of mental and physical well being, we also often find ourselves enthusing about it in a cult-like manner to sceptical passers-by, who wear regular winter clothing, and often a look of baffled awe. 

“It reboots, reminds and recalibrates. Things that seem insurmountable before a cold water swim are easier to tackle afterwards. It is not a cure all, but it helps!”

Such anecdotal accounts are also supported by science. Immersing yourself in cold water activates the sympathetic nervous system which increases the levels of endorphin (the happy hormone) and norepinephrine (also known as noradrenaline) which in turn can reduce levels of depression (Knechtle, et al., 2020). Research is also on-going to determine whether cold water swimming helps to prevent and reduce inflammatory diseases. At the same time cold water swimming  lowers levels of Homocysteine in your blood; High levels of this are linked to the early development of heart disease. Recent research by Susanna Soeberg (Soberg, 2022) indicates that it also activates your ‘brown fat’. The more you activate your brown fat, the more white fat you burn!

But (there is always a but), cold water swimming is known as an extreme sport for a reason. It may not take place at  high speed with increased odds of collision,  but the intensity of the experience on your body means you are pushing it to its limits. If you enter the water too quickly, you can suffer from Cold Water Shock Syndrome. If you stay in too long, Hypothermia, and after you get out you need to be aware of ‘After Drop.’ All of these put you at risk of serious harm or in a worst case scenario, death, but, they are also rare and all manageable. 

Cold Water Shock Syndrome can occur when you enter the water, and is recognised by your body responding automatically to the experience, by a sharp intake of breath, and an increased heart rate. To manage this, you need to enter the water slowly and in your own time. After a couple of minutes your body adjusts to the change, but if you are not aware of the possibility of this happening, or  are under water at the time (for example if you have dived in head first), it can be deadly. Cold water shock is a more common killer than hypothermia and the RNLI  have an extensive range of resources explaining the dangers linked to it. Because of the extreme change in your body’s behaviour during cold water swimming,  if you have any underlying health conditions,  it is important to consult with your doctor prior to starting.

Hypothermia occurs when your body's core temperature falls below 35 °C, and can result in a loss of consciousness and heart failure. To manage this, it is recommended that you acclimatise to cold water exposure slowly, over a number of occasions, and get changed quickly after exiting the water. It may be that on your first cold water session, you are only in the water for one or two minutes, but the next time, this may well increase, and so on. What is important to remember here, is that everyone's tolerance is different -  dependent upon water temperature, your build and experience. There is no magic formula to calculate how long you can stay in the water, you have to learn what your limits are. The first signs of hypothermia are shivering and loss of motor function in your extremities (your hands for example).  If you start to feel any of these symptoms, it is time to get out of the water.  Ideally you want to get out before you feel these, so finish your swim while you are  feeling good. Importantly, if you opt for wearing a wetsuit, rather than  skins, you may be able to extend the duration of  time that you are in the water, but, this does not make you invincible to either Cold Water Shock Syndrome or Hypothermia.

Afterdrop is when your core body temperature continues to drop for a period between 20-40 minutes after exiting cold water. As your body starts to rewarm through a process of heat conduction you will start to shiver, this may last longer than normal and make you feel a bit nauseous, woozy and exhausted afterwards if you've stayed in too long for you. If you have a bad experience of afterdrop, reduce the duration of your next swim, and get changed into warm, dry clothes as soon as you can afterwards. This is why cold water swimmers have perfected various ingenious ways of rapidly getting changed on the beach. There is no disguising that this is a tricky business,  and the sequence of removing wet garments and replacing them with dry cosy ones, is one that you can only perfect through personal trial and error. It is not a glamorous procedure, but once accomplished and you have a hot drink, a piece of cake in hand, and are surrounded by post - dip banter, you find a satisfying glow of comfort and achievement, even if you have no idea where your underwear is, and are talking through chattering teeth. 

A Hot drink, a hot water bottle, a snack and warm cosy clothes eases the edge of the cold water buzz into a contented, happy, cosy, glow. Photo credit Sandwick Bay Candles.

Finding a Pod

You now know how to theoretically manage some of the risks of cold water swimming, but one of the biggest safety precautions you can take is to start this new adventure as part of a group, or 'Pod'. This not only means that if something goes wrong someone can raise the alarm, it also means that as you stand nearly naked on an often brutally cold stretch of coastline, or shore of a loch, the sense of camaraderie required to de - robe and immerse is invaluable. Joining an existing group will also help you to develop knowledge of the local tide times, currents, safe entry points and hazards. It is however, important to be able to make your own decisions - only you know how your body is feeling, and if you feel safe and secure entering different types of outdoor swimming locations. It is important not to feel pressured into doing something that makes you feel unsafe, in doing so, any enjoyment and benefit you get from the experience will be removed. If you take things slowly, your confidence will develop, you will learn to harmonise with and listen to your body, and you will discover your own pathway of

well - being through cold water swimming. 

Finding a group of people to swim with can be a daunting task for newcomers, but Cold Water Swimmers are some of the happiest, most welcoming people you will meet.

Searching Facebook is a great way to locate groups in your area or start with an Open Water Coach if you want to learn the basics.


Things You Need to Think About, and Prepare

So a date and time has been set for your first dip. You have read everything you can find on saftey advice. But what else do you need to do, what should you take with you and what else could you do ?

What equipment do I need ?

The decision to swim in ‘skins’ or a wetsuit is entirely up to you, but advice from the RNLI is to wear a wetsuit. Some people start cold water swimming in a wetsuit and over time (and adjustment) try out ‘skins’. Some people who swim in ‘skins’ wear neoprene socks, gloves and a hat, others eventually just opt for straight skins (and maybe a bobble hat). The choice is yours, but either way, it is strongly recommended that you use an inflatable tow float. These indicate your presence in the water to other users but they are not life saving devices in the sense that they will keep you afloat if something

life-threatening happens. Their life-saving benefits lie in their visibility to other water users, plus some  have pockets, lights and whistles so you can alert someone if you are in distress. For getting changed, a wind and waterproof coat, and waterproof shoes are invaluable, and a towel and warm dry clothing to change into, essential (unless your house is within walking distance of the swim venue in which case lucky you, and you will make a lot of friends, very quickly in the cold water swimming world). 

'Skins' means swimming costume only. It does not mean naked.

Tow floats indicate your presence in the water to other users. Even on a bright sunny day, open water swimmers are hard to see in the water.

Water Temperature and the Weather

Cold Water Swimming is defined as swimming in water below 15°C (where there is evidence of cold water shock occurring). Between 8 - 9°C  conditions are ‘Very Cold’ and below 5°C is ‘Ice Swimming’ territory. As a comparison, the average indoor swimming pool temperature is 28°C and the human body ranges between 35 - 37°C. To help develop an understanding of falling water temperatures as a beginner outdoor swimmer,  a baby bath thermometer (often disguised as a yellow rubber duck) is a useful addition to your swim bag but it's important to remember that the air temperatures can affect an already cold body immersed in water so it's not all about the water temperature. It's true your body cools down 25 times faster submerged in water than it does in air of the same temperature but if you don't get dried & dressed quickly after a cold water swim you could prolong the post-swim rewarming phase so don't hang around in cool air post-swim. Get dried and covered up.

UK Sea Temperatures begin to fall in October and continue to do so until April, after which they begin to rise again. A good resource that collates average temperatures for different sea areas around the UK can be located via this link: 

Freshwater or Sea?

In Winter months freshwater lochs, lakes and rivers are colder to swim in than sea water. In summer months lochs can be deceptively warm when you first enter them but as you move away from the shoreline they get colder especially deeper lochs. In winter, shallow lochs cool down very quickly in line with the air temperatures and can be a lot colder than deeper lochs early on in winter. Swimming is freshwater has less buoyancy than the sea due to the density of freshwater so you might feel you need greater effort if you are used to sea swimming. If trying a body of freshwater for the first time don't swim out and away from shore, stay close to shore, within depth and swim up and down the shoreline. Generally, as your movement circulates the lower levels of the water (which are usually the coldest) the colder you will feel so don't go too far out.

A useful resource to look at, if you thinking of swimming in a particular freshwater location can be accessed here:

Although statistics and data are an invaluable resource, it is also worth remembering that the best source of information for a swimming location are the people who frequent it. These people remember everything their yellow ducks tell them. 

Swim Planning

It is good practice to plan your swims around weather conditions (and if relevant, tides). You can conduct your own reserach on these, using various apps. Here are some to get you started -  for tides and sea states, and for the weather and for general weather forecasting

Understanding Water & Weather

Prior to making contact with a local group you can also increase your safety knowledge and confidence by taking part in online or in person training events run by Immerse Hebrides and H2O Training.

Take a friend with you

If you are unable to find a swim group to join, why not ask a friend to sit and hold your towel and thermos for you? They may not be willing to join you in the water, but their presence will reassure you, and they can be called upon to provide proof to any sceptics, that you did actually get in the water!

Written by Netty Sopata with edits from Norma MacLeod

Further Resources

The Royal Life Saving Society (RLSS):

Rachel Andrews Every Day Athlete:



Deacon, A. & Allan, V., 2021. The Art of Wild Swiming Scotland. First ed. Edinburgh: Black and White Publishing .

Knechtle, B., Wa´skiewicz, Z., Victor Sousa, C. & Hill, L. N., 2020. Cold Water Swimming—Benefits and Risks: A Narrative Review. International Journal of Environmental Research and Public Health , 17(8984).

Soberg, S., 2022. Winter Swimming. The Nordic Way Towards a Healthier and Happier Life. First ed. London : MacLehose Press.

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