Thinking of trying wild swimming? Read this first

When summer comes around, ‘wild swimming’ tends to pop up all over social media with images of friends and influencers plunging into lakes, rivers, and the sea. Wild swimming is popular with people who enjoy the freedom of slipping into open water without the formality of a swimming pool, and instead spending time out in nature.

Health benefits of wild swimming

There’s some research suggesting it can have real mental health benefits, including helping to ease symptoms of anxiety and depression. Cold water exposure may also help your body become more resilient to stress, with potential longer-term effects on cortisol regulation and how we cope with pressure.

Although swimming in itself can be great for your health, there are some important safety precautions to keep in mind when wild swimming in the UK.

Dr Opel Baker, a GP at Mayfield Clinic in Brighton and Hove, talks us through some of the most common things you should watch out for when heading into open water.

Let’s be real - this isn’t Florida or the warm, turquoise waters you might picture off the Australian coast. This is the UK, and while we do get the occasional heatwave, our rivers, lakes, and seas are far from feeling like a hot tub.

Chances are, if you’re wild swimming in Britain, you’ll be plunging into water that’s lukewarm at best. Even on the hottest day of the year, water takes far longer to warm up than air, meaning the temperature of the sea, lake, or river rarely matches the weather's heat.

Cold water shock

That’s why even a baking hot summer’s day can still leave you vulnerable to cold water shock when you first get in.

According to Baker, cold water shock happens when your body suddenly enters cold water and triggers an involuntary “cold shock response”.

“Blood vessels in your skin rapidly constrict to preserve core body temperature, causing your blood pressure and heart rate to rise sharply,” he explains. “At the same time, many people experience an uncontrollable gasp reflex followed by rapid breathing or hyperventilation.”

Baker adds that this can make it harder to control your breathing, increasing your chance of inhaling water. For some people - particularly those with underlying heart conditions - the sudden strain on the cardiovascular system can trigger abnormal heart rhythms, chest pain, or, in rare cases, a cardiac event.

Muscle coordination and exhaustion

Cold water doesn’t just affect your heart, lungs, and blood vessels, it can also impact your muscle coordination. In these situations, it doesn’t matter how fit you are - the cold can quickly overpower your muscles and affect your ability to swim properly.

“Cold water quickly reduces your muscle strength, coordination, and endurance,” says Baker. “As your muscles cool, your nerve signals travel more slowly, and your movements become less efficient.

“Even very fit swimmers can experience ‘swim failure’, where their arms and legs become too weak to maintain an effective stroke.”

He explains that this can happen surprisingly quickly, especially in cold water. It may leave you unable to stay afloat or make it back to shore, even if you’re physically fit on land.

“Fitness does not provide immunity against the physiological effects of cold-water immersion,” adds Baker.

It should go without saying that wild swimming means swimming in water that hasn’t been treated with cleaning chemicals, like you’d find at a swimming pool.

Lakes, rivers, and seas are comparatively uncontrolled environments and home to a large variety of animals, organisms, and bacteria that you’ll be sharing your swim with.

Baker explains that wild swimmers can be exposed to a range of infections, including gastrointestinal illnesses caused by bacteria, viruses, and parasites present in contaminated water.

“One of the more serious infections is leptospirosis - commonly known as Weil’s disease,” he says. “This is spread through water contaminated with infected animal urine, particularly from rodents.”

Early symptoms of Weil’s disease can resemble the flu, including:

• Fièvre.

• Maux de tête.

• Douleurs musculaires.

• Des nausées.

• Perte d'appétit.

In some cases, the illness can progress and lead to:

• Ictère.

• Kidney issues.

• Méningite.

“Anyone who develops flu-like symptoms after freshwater swimming should mention this exposure to their healthcare professional,” Baker advises.

We’ve all seen those TV shows where, after a few shots of tequila, someone shouts “pool!” and everyone jumps in together. In reality, while it might be a common party moment, getting drunk around water isn’t the safest idea - and it’s definitely not something to do when wild swimming either.

Baker cautions that alcohol and wild swimming are a particularly dangerous combination - essentially, don't drink and dive.

“Alcohol impairs your judgement, coordination, and reaction times, making it harder to assess risks and respond appropriately in an emergency,” he says. “It can also increase heat loss by causing the blood vessels near your skin to widen, while actually speeding up how quickly your body loses heat.

“In addition, alcohol increases the likelihood of reckless behaviour and can reduce your ability to recognise the early warning signs of hypothermia or exhaustion.”

There are some warning signs that suggest your body has had enough during a swim, and it may be time to get out of the water and cut your session short.

Baker outlines the most common signs:

• Uncontrollable shivering.

• Difficulté à respirer.

• Vertiges.

• Confusion.

• Douleur thoracique.

• Palpitations.

• Muscle cramping.

• Extreme tiredness (fatigue).

• Difficulty coordinating your movements.

“A noticeable reduction in swimming strength or the feeling that you are struggling to make progress is particularly important and should never be ignored,” he says. “These symptoms can indicate the onset of hypothermia, cold incapacitation, or cardiovascular stress and warrant prompt action.”

If you’re thinking of giving wild swimming a go this year, it’s worth checking with your doctor first if you have any concerns about an existing health condition. Make sure you're aware of potential hazards, such as cold water shock and harmful bacteria, and ease yourself into the practice rather than diving in at the deep end.

Wild swimming can offer plenty of benefits, from exercise and stress relief to spending more time in nature. But like any outdoor activity, it comes with risks. Taking a little time to understand them - and recognising your own limits - can help make sure your experience is both enjoyable and safe.