Cold Water Swimming - Staying Safe

In 2022, Simon Griffiths of Outdoor Swimming Magazine, reported that out of the 4,500 swimmers taking part in an online survey the year before, one in five had admitted to starting outdoor swimming in the previous twelve months. There is no doubt wild swimming and cold-water dipping have massively increased in popularity over recent years, and are continuing to grow, but what of the safety implications? Is it really as simple as stripping off and jumping into the nearest body of water or sitting in a bathtub full of ice, or should we all be encouraged to exercise a little more caution?...

Like many, I was drawn to cold water swimming during and after the pandemic. I had suffered a serious back injury and was advised to stop running - my previous ‘headspace’ activity. I found being in the water calmed my mind, but the cold also eased the pain in my back, and after only a few dips, I was hooked! However, unlike many, I partook in a cold-water training class before I entered the water - my chosen wild swimming spot was the river Thames, and as I had only previously swum outside whilst on holiday somewhere hot, I wanted to be as informed as possible.

Cold water swimming at our seaside home on the South Welsh coast - in November...

Any body of water below 21C is considered to be ‘cold’, and as the average sea temperature surrounding the UK ranges from 6-10C in the winter months and 15-20C in the summer, these year-round conditions are enough to completely incapacitate even the most experienced of swimmers. Entering cold water will always carry risks and can trigger a series of involuntary bodily reactions whether you enter the water willingly or not, but being aware of these physiological warnings may potentially save your life or the life of someone you are with.

There are four stages of cold-water immersion failure. Any or all of these responses can be triggered by several factors, including the temperature of the water, the duration of the stay in the water, and the physical health of the person involved. The four stages are:

  • Cold water shock
  • Short term immersion (swim failure)
  • Long term immersion (hypothermia)
  • Post-rescue collapse

Known as cold water shock, the first reaction upon contacting the water is generally a gasp for breath, caused by the sudden cooling of the skin. If entering the water has been involuntary and unprepared due to falling or an accident and total submergence is involved, there is a high risk of inhaling water directly into the lungs. The inability to control breathing because of the cold and potential panic can cause hyperventilation and breathing to increase by approximately 600-1000 percent. It is therefore imperative to fight your instincts and relax as much as possible by using breathing techniques or by floating on your back until the shock passes. Drowning can take as little as half a cup of water entering the lungs of a fully grown man.

The sudden intake of breath is accompanied simultaneously by another primary response, known as peripheral vasoconstriction. This is where blood vessels near the skin, particularly your hands, feet, arms, and legs, narrow to shunt blood to the core in an attempt to protect the vital organs from temperature fluctuations. However, this in turn, can cause bodily stress as the heart works hard to pump blood through the constricted arteries and vessels, resulting in an increased heart rate, high blood pressure, and a legitimate threat of heart attack. Although it is difficult to determine an actual figure, a large number of deaths in cold water related incidents have been attributed to heart attacks, even amongst the seemingly young and healthy.

As your muscles cool, and if you haven’t been able to exit the water, your strength, endurance, and control will reduce. Cold water drains the body’s temperature at around 25 times faster than cold air. Manual dexterity can be lost in as little as 60 seconds, and the use of your arms in minutes - even competent swimmers will lose muscle control after approximately ten minutes. Cold induced spasms may add to the lack of control, leading to an inability to stay above the surface and resulting in a cold-water response known as ‘swim failure’. And if you are still unable to exit the water, find help, or a buoyancy aid, your limbs will become slow and heavy, and you will begin to lose power until you are physically helpless in the water. At this point, cold water incapacitation has set in, and it is likely you will drown.

Hypothermia is a condition where the body’s core temperature drops below the normal level of 36.5-37.5C and can be caused by prolonged exposure to cold water. It can take approximately 30 minutes to become hypothermic, even in really cold water, therefore if you haven’t managed to find a way to get out of the water and warm up, swim failure is still the immediate threat rather than hypothermia. However, hypothermia causes potential delayed risks and can lead to post-rescue collapse, which we will discuss further down.

A good indicator of the potential risk of hypothermia is when the water starts to feel warm and more comfortable, even though you know it should feel cold. This should be your cue to get out of the water and get warmed up. Other signs to be aware of are:

  • Constant shivering
  • Extreme tiredness
  • Confusion – slurred speech and/or memory loss
  • Drowsiness

If you think you or someone you are with are showing signs of hypothermia, get out of the water and get warm with dry clothes immediately. Make yourself or the person affected as aware as possible of the surroundings by talking and focusing on physical items. If memory is a potential issue, talk about something recent like what you had for breakfast. Core temperature needs to be raised, and this can be done with warm drinks and layers of clothing, coats, or blankets. Consider sharing body heat if needed, and appropriate.

Post-rescue collapse is the fourth and final stage of cold-water immersion failure. Known as the ‘silent killer’, it is characterised by a drop in blood pressure caused by hypothermia and can occur several hours after immersion. The person affected can become unconscious, stop breathing, and be at a high risk of cardiac arrest. Post-rescue collapse is the cause of 17 percent of cold water related deaths.

Obviously, there are exceptions to all these circumstances. Physical health plays a huge role in a person’s ability to withstand cold conditions, as does training and experience. In January 2020, British endurance swimmer and climate activist, Lewis Pugh, became the first person to swim under an Antarctic ice sheet, wearing just a pair of trunks, a cap, and goggles. Aiming to raise awareness of climate change, Pugh faced the threat of meltwaters and unstable glaciers, not to mention the freezing temperatures of the water. However, he was able to complete his challenge and become a world record holder due to his extensive training in frozen lakes, his intentional weight gain, and his use of a phenomena known as ‘anticipatory thermogenesis’ which increased his core temperature to almost fever levels to enable him to withstand the cold temperatures which would ordinarily kill a person.

Man swimming in an ice tunnel

Endurance swimmer and UN Patron of the Oceans Lewis Pugh swims down a glacial river underneath the Antarctic ice sheet, in East Antarctica on 22 January 2020. (Credit CNN)

But you don’t have to be ‘superhuman’ like Pugh to enjoy your experience in the water and safeguard yourself against cold water immersion failure. When I used to swim in the Thames, I always used a flotation aid in case I experienced difficulties in the water. Having a prop to help with buoyancy, whether a tow float or a life jacket, can increase your rate of survival in cold water by ten minutes without one, to approximately 60 minutes with one – that’s a crucial extra 50 minutes to either get yourself to an exit point or wait for help. It is strongly recommended to swim with at least one other person, but if you are swimming alone, a flotation device is essential.

People with hats on swimming in a river
Swimming in the Thames in the winter with friends, tow floats, and pom pom hats!

A big part of outdoor swimming is sharing the experience with likeminded people. Having another person with you, or dipping with a group, is a great way to ensure yours and everyone else’s safety. Be aware of yourself and the people around you and how you are all feeling, even if it is just through chatting and laughing as you dip – a quiet person could potentially be someone who is struggling and needs help. The social aspect of drying and changing together and warming up with a hot chocolate and some cake, is also the ideal opportunity for ensuring adequate recovery before everyone goes about their individual days.

Women in hats and smiling at the camera
Don't forget the all-important post swim selfie in hats and changing robes!

In summary, cold-water swimming, dipping, and immersion seems to be becoming more and more popular as people realise the health benefits, together with the relative ease of accessibility. To experience cold water therapy, you don’t necessarily need any specialist equipment as, while many are not fortunate enough to be near a body of water, nearly everyone has access to either a cold bath or shower. To enable you to fully embrace the activity, and if your budget allows, there are now a multitude of tubs and vessels to create your personal cold-water experience at home. Many in-person and online groups have been created to provide the opportunity to meet other swimmers, or to provide information and encouragement for those dipping in a tub on their own. However, it is important to remember that although the act of immersing yourself in cold water seems relatively simple, particularly in the comfort of your own home, the risks involved are high and should never be underestimated. Your swim or dip is what you are happy with and should not be seen as a challenge to have with others. You should never feel pressured to stay in the water any longer than what you are comfortable with, and if it doesn’t ‘feel’ right before you get into the water, don’t do it! I have a great passion towards cold water swimming, particularly as I have now traded the Thames for the South Wales coast due to a house move, but listening to your body and being as informed as possible before you embark upon your cold-water adventure could potentially save your life.

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