Get Ready To Winter Swim!

Follow the advice below to ensure you stay safe and get the most enjoyment out of your cold water swimming experience this winter!


swim in snow

1. Understand Cold Water Shock

When you get into cold water your body will experience the Cold Shock Response  – the cold water causes blood vessels in the skin to contract, which forces your heart to work harder to deliver oxygen to your major organs and muscle. Heart rate is increased and as a result the heart has to work harder to pump the blood and your blood pressure goes up. Cold water shock can cause heart attacks, even in relatively young and healthy people as cooled blood reaches the heart. If you have a heart condition (or family history of heart conditions) or asthma, seek advice from your GP before attempting cold water swims.

The sudden cooling of the skin also causes an involuntary gasp for breath. Breathing rates increase rapidly, which contributes to a feeling of panic. Breathlessness can be frightening but don’t panic, it’s normal and will pass. Cold Shock can ast for up to about 3 minuites. Try to relax and let our body accept the cold. You will be breathing in sharply but try to concentrate on breathing out slowly.  

The good news is that it is possible to train and become accustomed to Cold Shock Response quite quickly. After doing about 5 or 6 three minute cold water swims where the whole body (but not the head) is immersed, you should be able to halve your Cold Shock Response! 

Wetsuits do not completely remove the cold shock response when you get in as the cold water will quickly seep inside the suit. The wearer will still experience the Cold Shock response so the same care should be taken when entering the water. After a short while however the benefit of the neoprene kicks in and the layer of water trapped between the skin and the wetsuit warms up to help provide insulation against the cold.

2. Take A Cold Shower!

Not nice, but it’s the first thing you can do to help prepare your body for cold water! Take cold showers or baths to get used to the sensation of cold shock. The first dousing in cold water will be a physical and psychological shock but once your body is acclimatised you won’t get such a sudden increase in heart rate and adrenalin, which can cause you to hyperventilate in the water.

3. Keep Swimming!

The best way to acclimatise to cold water is just to swim in it often, at least once a week, and preferably more, gradually extending the time that you stay in the water. It is easiest way is to start your swimming in summer when the water temperature is warmer, and then keep on swimming through the autumn and then winter as the temperature drops.

Don’t set strict time or distance goals for staying in the water, use your head, not a watch! Get out when you start to feel uncomfortable or notice any of the signs of hyperthermia listed further down in the article.

4. Don’t Get Hung Up On Water Temperature

Don’t worry too much about the temp of the water every time you go for a swim. Once the water is under 10ºC degrees it will feel very cold when entering the water, and as it drops further even 1ºC feels like a big difference. The wind and outside temperature also make a difference, and some days you just feel better than others. It’s only by spending time in cold water that you get to know your limits but you don’t have to know the actual temperature to progress forwards. Every swim you do will be building your tolerance to the cold. Don’t push too far too soon and remember that the most important thing is to stay safe and to enjoy it!

5. Protect Your Extremities

Getting into very cold water (typically less than 10ºC) can cause numbness and pain, particularly in the extremities, such as the hands and feet. Neoprene socks and gloves can help protect your hands and feet and will dull the cold shock response. Wearing a bit of neoprene will extend the time you feel comfortable in the water by removing some of the most painful aspects of it, but still take care to notice other signs of hypothermia setting in. do some great neoprene accessories. Their Heat-tech gloves and socks that I’m wearing in the photo below are great for protecting your hands and feet – this water was 0.1 degrees!

Wearing two swim hats will help to keep you a little warmer and you can get bigger mask type goggles that will protect more of the sensitive skin on you face from direct contact with the cold water helping to reduce shock and the feeling of ‘ice cream head’ when you swim front crawl! 


ice swimming


6. Swim Safe!

It’s always safer (and more fun!) to swim with a friend or a group or to at least have someone on shore to keep an eye on you. Start out swimming in a well used swimming spot that you know is safe and then stay close to the shore or in water shallow enough to stand in. You should only venture into deeper water if you are confident you can swim the distance, being mindful of wind, currents and the cold.

Wear a bright coloured swim hat and a tow float makes you highly visible and gives you something to hold onto for a rest or if you feel worried.

7. Eat Well & Rest

To keep warm your body needs energy. The calories in your food are the fuel that your body will burn to produce heat so make sure you have eaten well and given your food time to be digested before you swim. If you swim without eating sufficiently or after other strenuous exercise when your body’s energy supplies are depleted you will find swimming in cold water much harder – you’ll feel more sensitive to the cold, will tire very quickly and will not be able to stay in as long as you otherwise might. Eat well and rest well before you swim if you want to stay in longer or go further! 

8. Should you ‘Warm Up’ Before You Swim?

Limbering up is important before exercise. It will open up your capillaries to get blood flowing around your body and bring up your heart rate slowly. ‘Warming up’ also delivers oxygen to your muscles to loosen them up for full range of motion. Whether you ‘warm up’ or not before cold water immersion is a personal choice, depending on body type, fitness and experience. Some people find getting in without any warm up works better for them, personally I like to ‘warm up’ a little as I find getting in easier and can stay in longer (but I am slim, very fit and acclimated well to cold water). The idea is only to do minute or two fast pace walk or gentle jog on the spot, just enough to increase your heart rate and get the blood pumping without increasing your core or skin temperature. Entering the water at normal body temp allows for the body to adjust to the cooler temperature of the water better and there is likely to be less of a Cold Shock Reaction than if you were to enter the water when too warm.

9. Wade In

Never jump or dive into cold water. Get in gradually by walking into increasingly deeper water, pausing for a moment once or twice to allow your submerged skin to adjust to the temperature of the water. Do not go out of your depth until the initial shock response has passed. As you wade in you can splash water onto your upper body and face to begin to get used to the temperature. Once you are in to your shoulders, dip your face in the water a few times before you start swimming properly so you can over come the Cold Shock response before you do anything too aerobic. Once swimming, try to keep moving and concentrate on keeping your breathing steady. 

10. Build Up Slowly

You may be able to comfortably swim 5km in the pool, but cold water combined with any wind, swell or currents demand more energy and can quickly sap your strength.

Cold water draws heat away from your body 25 times faster than cold air of the same temperature. As your body tries to recover that heat, it forces your heart and respiratory system to work harder, causing you to tire more quickly.

Do not swim out too far and always make sure that you have enough energy and stamina left to be able to swim back to your exit point. It is a good idea to stay close to the shore unless you have an experienced safety boat with you. Build up distance and times gradually, the same way you would build up the mileage for a run.

11. Cold Water Incapacitation

When you remain immersed in cold water your body continues to lose heat, blood shunts to the core to keep organs warm. As a result blood flow to your extremities and limbs is reduced and your muscles begin to lose power, limbs become slow and heavy, you start to feel very tired and swimming becomes increasingly difficult. You will lose your ability to control your hands and keep your fingers together (clawed hands) and the muscles in your arms and legs will eventurally stop working well enough to keep you above water – staying afloat can become very difficult. As soon as you start to notice signs of cold water incapacitation you should finish your swim!

12. Hypothermia & How To Recognise The Signs

Our core body temperature is normally stable but fluctuates (between 36.5ºC and 37.5ºC) depending on the time of day, the environment, our clothing, how active we are, how much body fat we have and how much energy we have (what we have eaten). 

Clinical hypothermia is considered a core body temperature of 35ºC, so it only takes a small drop in temperature to stop your body functioning normally and being in a serious medical condition.

Most people will feel the effects of hypothermia well before their core body temperature drops to 35ºC. Spotting the signs of hypothermia can be hard when you are in the water but these are some signs to look for in yourself and your swimming companions:

  • Shivering and cannot stop voluntarily
  • Slurred speech or mumbling, they may have clenched jaws.
  • Confusion or memory loss, and may not be able to answer questions coherently. One trick is to count to 10 and then back to one, over and over again. If you lose your train of thought or lose count, it is definitely time to exit the water.
  • Their stroke rate has dropped and they have slowed down.
  • Their position in the water has become more vertical so you don’t see their feet kicking, their kicking will also have slowed.
  • They are splashing excessively due to a deteriorating quality of arm stroke
  • They look pale and have a blank, lost expression
  • They complain of cold
  • They have a lack of reasoning and an inability to gauge their own condition saying they can keep going even when it is obvious that they can’t. As blood cools in the body it becomes thicker so less oxygen gets carried to the brain. The resulting confusion means you they’re unable think clearly.
  • Their teeth are chattering
  • They suddenly start to feel warm again
  • Manual dexterity is reduced, a common symptom is splayed fingers and the inability to keep them together when swimming, know as Clawed hands.

If you or anyone you are swimming with begin to experience any of these symptoms get out the water immediately and begin slow rewarming by dressing in dry clothes, warm sugary drinks and lots of shivering.

13. Shivering

Shivering is stimulated to increase deep body temperature when a reduction in deep body temperature occurs. It works by involuntary contraction of the muscles to generate heat.  A swimmer who is experiencing violent shivering (Moderate stage Hypothermia) should be removed from the water immediately. How do you tell violent shivering from normal shivering? Normal shivering can be stopped voluntarily, violent shivering can’t!

14. Understand ‘After Drop’ & The Safest Ways Of Re-warming

re-warming after swimmingWhen you finish a cold water swim, you continue to cool down for approximately 20-30 minutes as your body sends blood back away from your core to your limbs and the cooler blood from your extremities heads towards you core. This means that your deep body temperature will be cooler 20-30 minutes after your swim than your were when you got out of the water. When you first get out of the water you may not be shivering but within a couple of minutes you will begin to shiver a lot and will feel increasingly cold. This response is known as ‘After Drop’. It can be a pretty unpleasant feeling as the cold blood begins to move, a bit like a creeping cold hand going down your back and then a growing cold feeling right in your middle.  

It is essential that you get dry and changed into warm clothes warming up immediately after you exit the water. The safest way to re-warm is to:

  • Remove your wet clothes and dry off as soon as possible.
  • Dress in dry warm clothes, including hat gloves and thick socks – ideally lay these out in advance so you can do this quickly and avoid clothing with fiddly buttons, hooks and zips as your hands will be too cold to deal with them.
  • If you are changing outdoors have a insulated mat to stand on
  • Put on a hat over your swim hat to avoid any further heat loss until you have finished dressing. 
  • Have a warm sugary drink ready in a flask. Just warm is best as hot water on very cold lips can feel scolding. Only half fill your cup or use a cup with a lid as when you shiver you will spill your drink!
  • Shivering is good – it is your body’s way of generating internal heat. 
  • Eat high calorie food to replace the energy you have lost. Your body needs energy to keep producing heat! 
  • Get out of any wind and preferably into a warm indoor environment.
  • Use a hot water bottle or heated car seat to gently help add warmth. 
  • Do not drive until you have warmed up properly.
  • Do not jump straight into a hot tub or hot bath/shower! This can exacerbate the effect of After Drop. Your body needs to rewarm slowly and naturally. 

15. Read Up & Reach Out

There are loads of good articles about cold water swimming and the topics covered above available on the internet. Do some research and read up on other people advice and experience. You can reach out to swimming societies for further advice and to swimming groups on social media to find other people to swim with and suitable places to swim. There are some open water swimming venues that remain open all year with life guards and companies that offer supported training swims.

Good luck with your winter swimming! 


Written by Chloë Rafferty, Love SwimRun Organiser and Open Water Swimming Coach. Updated 12/10/20