Charlie Evans, ASCTA Coach, experienced ultra-marathon open water swimmer and enthusiastic underwater photographer.


The health benefits of cold-water exposure are well documented and can be readily researched. This document is not about outlining those benefits but instead, enabling you to undertake the activity as safely as possible.

Cold water swimming has a high level of risk associated with it and all care and due diligence should be taken and sought before beginning any activity. Talk with your swim buddies about this risk and make sure all are fully aware of the potential hazards, these may include: Hypothermia, panic attacks, jellyfish stings, cuts and abrasions caused by contact with reef, pulmonary oedema, wildlife bites, heart attack or drowning.

Cold water swimming does not have a strict definition. However, ice swimming does, for example to qualify as having successfully completed an ice mile one must swim for 1.6 km unassisted at a temperature at or less than 5 degrees Celsius. We all experience the cold differently and a challenge for one may not be a challenge for another.

There are no rules around being a skin swimmer or wearing a thermal suit of some kind, the only rule is wearing something that you are comfortable in and which does not cause you to feel unsafe. Living in the Southern regions of Australia our waters cool significantly during the late Autumn and Winter months with a very general ocean and bay range from 8c – 23c. Inland water-ways will be more extreme and can get both warmer and much cooler, 5 degrees Celsius can be found in the central alpine regions during the Winter in New South Wales, Victoria and Tasmania.


Before entering the water, it is recommended that participants undertake some form of dry-land warm up or stretching drill to activate the specific muscles used during swimming. A good example may be some superman drills and including a kick, shoulder rolls, pectoral stretches, lunges, and squats. Some may prefer a light run or bike session and all have benefit due to their ability to increase the heart rate a little and preparing the body for exercise.

Never attempt cold water swimming alone. Always have a swim buddy, preferably someone with more experience than you. Always wear a bright swim cap, fluorescent is best, and Pink has been shown to be one of the most visible colours to potential rescuers. Use a swim float if you have access to one, these are brightly coloured inflatable tow-floats that enable you to be seen, rest, and store a communication device, keys, nutrition etc. Some swimmers choose to wear gloves and booties which will keep your extremities warm but many find that these items do affect your “feel for the water” and therefore can have a negative effect on your stroke and potentially endurance.

Start small – endurance swimming and cold-water swimming are separate skills. Cold-water acclimatisation takes time and like other pursuits a plan to build slowly is sensible. Use the 10% rule as a good guide. Start with a plan to achieve 10 minutes in the cold, repeat this a few times before increasing your exposure by 10%. Initially swim a course that is close to the shore and always within reach of your base and a re-warming location and support crew. Proper acclimatisation and confidence may come over a period of several seasons. Let people know before you go and leave clear plans with a trusted person. Never change your plans without letting these people know. Leave a map if you are heading to an isolated location.

Entering the water

 All open water swimmers experience some level of anxiety when entering the water particularly when the water is cool/cold, and the air temperature is warmer upon entry. No swimmer enters the water without experiencing some level of cold shock response whether minor or otherwise. Most experienced cold-water warriors are simply better at hiding that cold shock from you. Anecdotally I know that 19c is a doddle for some but a real challenge for others. Never forget that your body runs at around 37c and at some point, the balance WILL be lost, and the cooler water will cause your core temperature to drop.

Warming from the inside out is best and we will talk about this again later but consuming a warm drink, for example sweet tea before you enter the water is a great way to increase your body temperature a little. Breathe! Take your time, open your airways, and undertake some yogic breathing if this something you are comfortable with. Never rush your entry into the water. If you are planning a longer swim carry a warm drink (in your tow-float) and or some light liquid-based nutrition (gels, baby food fruit squeeze packs, electrolytes all have benefit). Make sure your diet includes foods high in magnesium (broccoli for example) as this will help to increase blood flow and reduce cramps. Cramps are significant risk to open water swimmers and need to be planned for and managed with great care. Consider a magnesium supplement if your diet shows an inadequacy in this area.

Entering the water is not a competition, everyone has their own technique for doing this. I like to walk out slowly to waist height whilst deep breathing. My hands enter the water next as they have a strong sensory function in the body and help balance your system, I normally hold at this point for a minute or so. If the water is cold enough you may even experience a burning sensation as your brain struggles to understand the difference between hot and cold, this is normal, and it will pass. Ice cream-headache as your body balances the temperature is also common.  

At this point I am ready to dunk; I do this and stay under for as long as I can before bobbing up with shoulders remaining under the water. I hold here again for up to a further minute; I am then ready to start moving forward and begin gradual slow swimming in any stroke until I feel comfortable (up to a few minutes). During this period chat with your swim buddy and confirm your plans and swim course. Confirm that you are both/all feeling comfortable and ready to proceed. If you do proceed and things go wrong, for example you have goggle or equipment issues, you feel anxious or colder than expected, never simply change your mind, and leave the water.

You must communicate this with your swim buddy and make sure they are clear, never put them in the position where they feel they may have lost you; this can cause great panic. The next phase is important and is broadly described as a warm-up. Move into your preferred stroke causing the blood and oxygen in your body to begin doing their job and allowing you to settle int a consistent and comfortable stroke. Breathe evenly using your diaphragm to allow extra space in your lungs by raising your ribs via your intercostal muscles. Diaphragm breathing can also help to reduce anxiety. A warmup can happen over a couple of hundred metres or in some cases over a much longer period.

The swim

Swim your planned course, settle in and enjoy all the new sensations and messages you are being sent as your mind and body is triggered. Feel T by the experience but let go of your “monkey mind” and find some level of meditation within your swim practice. Be aware and careful of the fact that your mind may play tricks causing you to feel better or worse physically than is the actual case.

Time to exit the water

Recognising the right time to leave the water is also important. This is not as simple as it sounds and noticing differences in the way you feel, and your body works is especially important. Clinical hypothermia occurs when our body temperature drops to 35 degrees Celsius. Leaving the water early, safely and in good condition will maximise your experience of an enjoyable challenge, leave it too long and your experience may be vastly different.

Most people will feel the effects of hypothermia well before their core body temperature cools to 35c. These signs include mental confusion, clubbing hands, numbness, slurred speech, a feeling of euphoria or unusual warmth and or poor movement and coordination. At this point it is always recommended that if you are with a swimmer in this state or feel symptoms yourself that you are quickly evacuated from the water.


Once you or the swimmer has left the water the process of rewarming can begin. Rewarming is a slow process noting that once you exit the water you will continue to cool for 20-30 minutes. This means that your deep core body temperature will be cooler in 20-30 minutes than when you first exited the water, so warming quickly is vital. The safest way to rewarm is to seek shelter: dry off and remove wet swim kit and towels as soon as possible.

Dress in warm dry clothes including a hat, gloves, and thick long socks. Ideally have all this clothing prepared in advance for every swim as this will always improve your post swim experience. Have a warm drink, sweet black tea is effective. Shiver! Shivering is good as it is an automatic response from the body causing your muscles to contract and relax quickly producing friction and warmth. As you warm you will shiver less. Keep yourself and others safe by waiting until you are fully rewarmed before leaving a safe location or undertake any risky activity such as driving.


Allow a recovery period before your next swim or cold-water exposure. Research your diet and nutritional needs to become strong in your new environment. Plan your next swim in advance, collect data keep records, adjust and be open to changes to your technique and methodology. Ask yourself the “why” question and set goals accordingly. Search out knowledge and delve deep into the benefits to your mind and body of cold exposure.

Swim with regularity during the cooler season, less than once a week will not cut it and a bare minimum of once a week should be your goal. The more often you expose yourself the quicker the acclimatisation will occur and the greater the reward. Be open to the potential outcome that this may not be for you, you are not a failure! Every body is different.


After reading this article I hope you are inspired and motivated to attempt a cold-water swim no matter your age or swimming prowess. There has been so much literature produced around the benefits that I am sure you will be prepared and excited by the prospect of improving your physical and mental health via cold exposure. My number one message to you is to be safe and never attempt cold water swimming alone. Go on a journey with a swim buddy and build a friendship based on your adventures together. Be energised and have fun!

Additional notes

Ear plugs: ear plugs can offer huge benefits to Cold-water swimmers protecting them from surfers or swimmers’ ear (Exostosis) which causes an abnormal bone growth in the ear canal. The bone growth in itself is not necessarily dangerous but instead allows dirt and debris to become caught in the ear canal. In more severe cases the bone growths can become so great that it can cause hearing loss and or balance issues. Swimmers ear is most often caused by repeated exposure to cold water and those who spend extended periods outdoors in cold wind or rain, for example some tradespeople.

The use of ear plugs whilst swimming can protect ears and reduce the onset of such growth. Ear plugs may be silicone, foam or moulded to the individual by an audiologist. Some swimmers choose to use products like “Bluetac” however, there is some risk of this type of product softening or breaking down over time and causing debris to become lodged deep in the ear canal. Swimmers must be careful not to remove and replace ear plugs during their swim practice as this will also force water and debris further into the ear again causing discomfort and blockage. I never enter the cold water without high quality silicone plugs.

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