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A swimmer wearing a bright pink cap glides through the water, with an orange inflatable tow float bobbing behind her

What are the benefits of cold water swimming?

From rivers and reservoirs to the ocean itself, thousands of us are diving in and discovering the benefits of cold water swimming.

Dip your toe into the bracing world of sea swimming and learn about the physical and mental health benefits, from boosting your mood and immune system to improving your fitness levels and circulation.

Here are just a few reasons people love a cold water dip:

  • It can improve your fitness levels and your metabolism.
  • It may help with aches and pains. 
  • It can improve your circulation. 
  • It may help to boost your immune system.
  • It helps some people manage their mental health.
  • It can reduce your stress levels.
  • It can help people find a community by meeting friendly fellow swimmers.
  • It gives you a natural high, leaving you feeling euphoric and exhilarated. 
  • It’s a great chance to get out and about in nature.  

Ready to find out more? Let’s dive in.

A swimmer wearing a wetsuit steps into the Belmullet tidal pool near Ballyglass, with three other swimmers already waist-deep in the water

RNLI/Nigel Millard

Thinking about braving the cold? Here are the benefits of open water swimming

It can help you keep fit

Cold water swimming – sometimes referred to as open water swimming or wild swimming – is a great way to stay fit throughout the year. Swimming for just 30 minutes a week can even help to guard against heart disease, stroke and type 2 diabetes.

As well as improving your muscle strength, swimming is one of the most effective ways to burn calories. And cold water can increase your calorie burn rate too. But remember, the colder the air and water temperature, the quicker you will cool down. So, the colder it is, the less time you should spend in the water. 

Average Irish and UK sea temperatures are just 12°C and rivers are colder - even in the summer. If you’re sea swimming during the colder months or for extended periods, wear a wetsuit of appropriate thickness.

Catherine smiles at the camera, wearing a red swimming cap

Credit: Anna ‘nudi’ Burn

Catherine, a member of the cold water swimming group Frosties

It can even improve your circulation

Catherine is part of the Frosties, a year-round swimming group in Skerries, on the north Dublin coast. She swims with her group at least twice a week without fail, all year round, even in the sleet and snow.

Catherine originally got into open water swimming after an injury. ‘It’s great for the circulation. Cold water numbs everything and it’s invigorating,’ she enthuses.

Over time, cold water exposure redirects blood flow to your vital organs, encouraging your body to circulate blood more efficiently and effectively.

But remember, cold water swimming is very different to swimming in a pool, so you should never swim alone.

The safest way to wild swim is at an open water swimming site, with a club or between the red and yellow flags on a lifeguarded beach. If you can’t get to a lifeguarded beach, learn more about your chosen location and check hazard signage by finding an organised swim group in your local community.

It's a good way to make new friends

Other benefits of cold water swimming include the great sense of community you'll find. Nothing brings people together like facing a challenge and sharing the experience as a group, so it’s a great way to make new friends.

There has been a surge in the popularity of open water swimming in recent years, helped by the rise of triathlons and marathon swimming. But for many groups, it’s not just about speed or long distances.

As many as 80 people go out swimming each time with the Frosties, covering around a mile in about half an hour.

The Frosties welcome newcomers and triathletes to the group. Catherine says: 'If we see someone new we advise them about local currents, rocks, jellyfish (in summer) and places to get out when they get tired.

'Whatever your speed, I recommend you join a club - there’s a very big social element to it. It’ll give you a real boost.'

To find out where you can get lessons, or to join an open water swimming club, visit the Swim England or Swim Ireland websites.

Cold water dippers are swimming in a tidal pool. They’re all wearing wetsuits and swimming caps.

Credit: RNLI/Nigel Millard

There’s a real sense of community and solidarity among cold water swimmers

Could cold water swimming boost your immune system?

Many open water swimmers believe a cold dip can boost their immune system. So we asked our friends at the Extreme Environments Laboratory at the University of Portsmouth whether there was any truth to the common claim that icy cold swims fend off the common cold.

Professor Mike Tipton MBE and colleagues at the Extreme Environments Laboratory at the University of Portsmouth published a paper on this topic. Key conclusions highlight that the jury’s out: ‘There is some evidence that the short stress of CWI [cold water immersion] may prime the immune system to deal with a threat, and thus be beneficial … The definitive studies in this complex area await completion.’

A swimmer’s arm splashes through the open water, with sea spray

RNLI/Nathan Williams

Could a cold water dip help boost your immune system?

It's a natural painkiller

For years, cold water therapy has been used by athletes to tackle sore muscles and nagging injuries. Some people even claim a short cold water plunge can act as an alternative to strong painkillers! 

But remember, when you go sea swimming, or any form of open water swimming, it’s very important to enter the water slowly and allow time for your body to get used to the cold. Never jump or dive straight in, as this could cause cold water shock.

It can be good for your mental health

It’s the mental benefits of sea swimming, not just the physical, that appeal to so many swimmers. Many believe a cold water dip can boost your mood and lower stress.
As Catherine from Frosties says: ‘It’s great stress busting. It has real benefits for people who are depressed. It’s my outlet – it keeps me mentally in shape.’


Like all exercise, swimming boosts dopamine levels and releases endorphins in your brain, helping you to feel content and relaxed. Catherine says many in her group have high-pressure jobs. ‘Just half an hour swimming a few times a week has a calming effect,’ she says.

A swimmer wearing a yellow and white swimming cap and gold goggles grins at the camera

Credit: RNLI/Nigel Millard

Open water swimming can help you feel calm and content

Can open water swimming help with anxiety?

We know that cold water can affect our brains as well as our bodies. When you immerse yourself in cold water, your body’s fight-or-flight response is triggered, which releases cortisol – the stress hormone. The more often you take dips in cold water, the more your brain gets used to the cold and lowers these stress hormones.

Plus, the feeling of cold water on your skin, combined with being outside in nature, can encourage mindfulness and wellbeing. Some feel that open water swimming brings them into the present moment and deepens the connection between their body and mind.

To make your next cold water dip stress-free, come prepared with these safety tips:

  • Check the weather and tide times before you go, and don’t swim in dangerous conditions.
  • Take a means of calling for help in a waterproof phone pouch, and have this on you at all times.
  • If you see someone in trouble, call 999 or 112 and ask for the coastguard.
  • Wear a brightly coloured hat plus a tow float for increased visibility.
  • Always swim parallel to the shore and not straight out. Cold water, waves and currents can tire you out quickly and make it harder to return to shore. 

And finally, if in doubt, don’t go out. No matter how much preparation you do, or how experienced you are, if a swim doesn’t feel right there is no shame in getting out of the water straight away, or not entering.

Whether you're swapping the swimming pool for open water or enjoying a quick dip, here's how to stay safe.

Get open water safety tips