Swimming in cold water offers numerous mental and physical health benefits. Many swimmers report improved circulation, reduced stress, and better mental health. Swimming regularly in cold water releases endorphins, helping to alleviate depression and anxiety​.
However, it is vital to remember that cold water swimming carries risks and many of these should not be taken light heartedly. Preparing properly and understanding the body’s reaction to cold can help you swim safely. Although we are not medical experts, here’s a guide to ensure you know how to safely swim throughout winter and in cold water.
What are the key risks?
Cold Water Shock
Cold water shock occurs when you suddenly enter water below 15°C (59°F), triggering an involuntary gasp. If you are under the water when this involuntary gasp occurs then you may inhale some water. Quickly following on from this initial gasp is a period of uncontrollable rapid breathing and increased heart rate. This can cause panic, hyperventilation, and, in severe cases, drowning. The shock phase usually lasts for about one minute.
To avoid cold water shock, always enter cold water gradually and avoid jumping. Acclimatise to the conditions slowly​, stay in the water during this period of cold water shock response and begin swimming after the minute has passed and when breathing is more controlled. If you feel yourself panicking then follow the RNLI’s Float to Live advice and float on your back with your arms spread out and try to relax.
Cold water incapacitation
Typically after the initial effects of the cold water has worn off, the water may seem somewhat comfortable and a swimmer may begin crossing the lake. As cold water diverts blood flow from your limbs to your core, your muscles may weaken, making swimming more difficult.Â
As well as monitoring your muscles and limbs, you can also do a quick manual dexterity check touching your thumb to each finger on each hand. Ultimately, it’s vital to avoid overexertion and, when always swim parallel to the shore line to facilitate a quick exit if needed​.
Hypothermia
Prolonged exposure to cold water can lead to hypothermia, where your body temperature drops below 35°C (95°F). If left unchecked, hypothermia can be fatal. Recognizing the signs and knowing when to exit the water is essential​. Symptoms include confusion, disorientation, and loss of motor control.
How to stay safe?
Slow Entry:
Never jump or dive into cold water. Instead, enter the water gradually, giving your body time to adapt to the cold. Sudden immersion can trigger cold water shock, an involuntary reaction that includes rapid breathing, increased heart rate, and a loss of control over breathing.
Acclimatization:
Start with short dips, gradually increasing the time spent in cold water to help your body adjust. This slow acclimatization will reduce the likelihood of cold water shock and allow your body to develop tolerance. Before entering, it can help to splash cold water on your face, wrists, and ankles to prepare your body for the temperature change.
Swim Parallel to Shore:
Once in the water, swim parallel to the shore rather than heading straight out. This helps ensure that you can exit easily if you become fatigued or cold. Cold water causes rapid energy loss, so plan your swim route to allow for an easy exit.
Limit Your Time:
Even with acclimatization, cold water can rapidly drain your body heat, so limit your swim duration. A general rule is 1 minute per degree Celsius of water temperature if you are swimming without a wetsuit. This doesn’t mean that you must stay in the water for 10 minutes if it is 10 degrees, if you start feeling excessively cold or notice any of the signs listed below, exit the water immediately to prevent hypothermia. It doesn’t matter if the week before you were capable – the body’s ability to withstand the cold water can be affected by numerous factors from the food consumed before the swim to how tired the person is.
Monitor Your Condition:
Pay attention to how your body feels. Symptoms like numbness, stiffness, or shivering are signals that it’s time to get out. If you’re swimming with others (which is strongly recommended), keep an eye on each other’s wellbeing.
Weather and Water Conditions:
Always check the weather, tide times, and water temperature before going swimming. Conditions like rough seas, strong currents, or extreme cold can increase the risks. If conditions are unsafe, do not swim.
We strongly advice swimming at official open water swimming sites or lifeguarded beach where conditions and swimmers are monitored.
Swim with Others:
Never swim alone. It is safer and more enjoyable to swim with a buddy or a group, ideally with an organized swimming club.
Avoid Alcohol(!!):
Never swim under the influence of alcohol as it impairs judgment and affects your body’s ability to regulate temperature.
What equipment do I need?
Wetsuits
Wearing a wetsuit is highly recommended, especially in water temperatures below 15°C. A wetsuit not only provides insulation but also increases buoyancy. When wearing a wetsuit, make sure it is the correct kind. For example, a wet suit normally worn for surfing is made differently to those worn when open water swimming and the extra absorbency can hinder your swimming ability.
Stay visible – Swim Cap and Tow Float
It is vital to wear a brighly coloured swim hat when open water swimming. This helps others to spot you. The best colours to wear are bright yellow, orange or neon green or neon pink. You can enhance your visibility further by using a tow float.
Protective Equipment
Consider using neoprene gloves and booties for additional warmth – you will be surprised how much these can help.
It is also a good idea to carry a means of communication, like a mobile phone in a waterproof pouch, in case of emergencies.
How to get warm post-swim?
Post-swim recovery is extremely important as hyperthermia can still occur after exiting the water especially if steps to re-warm the body are not taken!
Once out of the water, dry off immediately and put on warm, dry clothing. Focus on warming your core by using multiple layers of clothing (thermal if possible), warm fluffy socks, gloves and a warm hat. A good tip is to keep your swim hat on until all top layers are on and then swap it over for a nice warm bobble hat.
NEVER jump into a hot shower straight away after swimming in water less than 15 degrees. This can cause a rapid drop in blood pressure, known as afterdrop, which can make you faint or feel dizzy and disorientated.
The better way to warm up your core temperature is to drink hot drinks and use hot water bottles to gradually increase your core body temperature.
Wait for 30 to 45 minutes before driving as afterdrop can occur even as your body temperature increases and the sudden shivering which can follow can make driving dangerous.
By following these guidelines, you can minimize risks and enjoy the invigorating benefits of cold water swimming safely. Whether you’re an experienced swimmer or a beginner, preparation and awareness are key to ensuring a safe and enjoyable experience.