10 science-backed benefits of cold-water swimming

Cold-water swimming, also known as open water or outdoor swimming, can provide you with a vast host of benefits when done safely. It usually takes place in lakes, rivers, or even the open ocean.

People have been immersing themselves in cold water for thousands of years, and the numbers tell a clear story: regular open-water swimming among UK adults more than doubled in under a decade, from around 266,000 people in 2016-17 to 543,000 in 2023-24, according to the Reconomic 3.0 report backed by Swim England [1].

In this article we’ll explore some of the advantages of cold-water swimming, plus how to do it safely. Ready to learn more? Let’s dive in.

Why is cold water swimming good for you?
 

Swimming in general is one of the best forms of exercise, as the buoyancy we experience in the water make it low impact – suitable for people with reduced mobility or chronic pain, such as joint pain.

For many people, swimming in heated pools or warm natural water at temperatures of around 21°C is a preferred way to get fit, build endurance, and relax. But for others, cold-water swimming – where temperatures are 15°C or under – offers an extra challenge, and additional set of health benefits.

While the initial plunge can feel uncomfortable to say the least (more on why plunging isn’t necessarily the best way to get into the water later), it’s thought repeated exposure can help the body adapt to cold temperatures. Add to that the energy and mood boosts, improved circulation, and potential recovery benefits, it’s perhaps unsurprising that people who have tried it say they can’t imagine life without cold-water swimming. Let’s take a closer look at what the science says about some of these advantages.

1. Does outdoor swimming help with anxiety and depression?
 

Have you ever swum in the cool sea or lake, and climbed back out again feeling refreshed, exhilarated, and breathless? Well, you’re not alone – the most frequently reported benefit of cold-water swimming is the boost it can give your mood.

The evidence base has grown considerably in recent years. A Danish feasibility study found that supervised cold-water swimming was safe and beneficial for patients with clinically diagnosed depression, improving sleep and general wellbeing [2].

Separately, a UK trial run by the University of Portsmouth is now building on an earlier successful study into outdoor swimming as a treatment for depression [3]. The exact mechanisms are still being unpicked, but the direction of the evidence is increasingly positive.

2. Can cold-water reduce inflammation and arthritis pain?
 

Much anecdotal evidence suggests that cold water exposure is beneficial for those living with chronic pain caused by conditions such as arthritis [4]. Arthritis is a long-term, inflammatory condition that causes pain, swelling and stiffness in the joints.

There’s a couple of reasons why cold water may help.

Firstly, the buoyancy we experience in water means our joint pressure is relieved. This makes exercise easier, which in turn produces endorphins and helps to reduce inflammation [5].

Secondly, the cold can, in some cases, act as a natural anti-inflammatory, although the effects may simply be due to a 'numbing effect' caused by the cold on our bodies (similar to applying an ice pack) [6].

More robust research is needed, so experts cannot yet recommend cold-water therapy to treat health conditions, but it is reassuring to know that researchers are working hard to uncover the real benefits on our bodies [4].

3. Does cold-water swimming reduce stress?
 

When you plunge your body into cold water, it briefly activates the sympathetic nervous system – a.k.a. your body’s fight or flight response.

Your heart beats faster, your breathing becomes more rapid, and your body releases stress hormones such as adrenaline alongside mood-enhancing chemicals like endorphins.

So, how does this reduce stress?

While it may sound counterintuitive, regular exposure to short-lived stress can actually help the body become better adapted to coping with stress over time. Studies are even investigating whether cold water therapy could be useful in treatment of post-traumatic stress disorder (PTSD) [7].

4. How does swimming in the cold affect metabolism?
 

Some scientists have found benefits to metabolism from cold water exposure, for example through the activation of brown adipose tissue (BAT) in our bodies. BAT is considered a 'healthier' type of fat in our bodies, which can help keep us warm by turning glucose and fatty acids in our blood into heat [8]. In theory, this may support the body to burn more calories, but more research is needed on this exciting topic.

Activating BAT through cold water swimming may also improve insulin sensitivity [9] and lower blood sugar markers, although if you have diabetes you should consult with your GP beforehand.

One (proven) way to support your metabolism is through muscle strengthening and exercise, such as swimming. So, whether you choose to swim in the warm or cold, it can only be beneficial for your metabolism.

5. Can cold water swimming affect your heart?
 

Swimming is great for improving your cardiovascular health, but if you have a heart condition you need to be careful.

When we swim, our heart works faster – this is partly why swimming is good for your heart. But the colder the water, the harder our heart needs. Suddenly submerging your body in very cold water can cause “cold shock” [10].

Over time, it’s thought that regular cold swims may improve your circulation and blood pressure, but it can also cause cardiac stress such as abnormal heart rhythms or heart attacks [11]. More research is definitely needed, and if you should always consult with your GP before trying cold water swimming.

6. Is cold water swimming good exercise?
 

Swimming is a great all-around type of exercise because it can strengthen your cardiovascular fitness along with strengthening your muscles.

Regular swimming can reduce the risk of chronic diseases, such as heart disease, type 2 diabetes and stroke [12].

What's more, swimming in water can support the bodies of people with injuries or certain disabilities. Meaning that everybody can get involved.

8. Does cold water swimming help DOMS?
 

Exercise can lead to pain and sore muscles, also known as delayed onset muscle soreness (DOMS). Many elite athletes use cold therapy (also known as cryotherapy) to support muscle recovery and reduce pain after a bout of extreme exercise [13,14].

Some even take ice baths but the jury is out as to whether this is better than heat therapy. Experts highlight that this treatment may not be appropriate for all types of exercise and more research is needed to unravel whether heat therapy may be just as beneficial [13,14].

9. Connect to nature
 

Many wild swimmers say that whilst you are in the water surrounded by water and wildlife it gives you a sense of intense mindfulness which is difficult to achieve with any other activity. This is because when swimming all you can think about is the 'here and now' - your movement in the water, your physical surroundings and whether your body is warm enough (or whether it is time to get out!).

What's more, swimming in many undisturbed stretches of water allows you to adventure into unexplored areas of nature which you may not be able to access on pre-determined footpaths. You will gain a different perspective (literally) on the UK's landscape offering the chance to catch a glimpse of some rarities of nature.

10. It's fun (and free)
 

Outdoor swimming offers the chance to meet others with the same interests as you and in many cases (such as wild swimming) you can participate entirely for free. With an endless number of locations across the UK, there is always somewhere new to explore.

Or why not join a local group and buddy up with others? This is a great way to get to know people and learn techniques from those who are more experienced. Your swimming group can become a new weekly social event which is a great and enjoyable way to blow off steam and have fun after a busy week at work.

How to do cold-water swimming safely
 

Before beginners jump in at the deep end (excuse the pun), it is important to get savvy on the safety of cold-water swimming.

The single biggest risk is cold water shock – a physiological reaction to sudden cold immersion that causes involuntary gasping, a spike in heart rate and blood pressure, and is a major factor in open-water drowning incidents in the UK [15]. It typically hits within the first minute of entering the water, which is exactly why the precautions below matter.

Safety precautions:

• Beware of boat traffic
• Take it slow
• Check the currents and tides
• Make sure you’re a confident swimmer
• Consider having a float, even if you’re a strong swimmer
• Watch the weather forecast
• Monitor the temperature
• If you have a heart condition, seek medical advice first
• Buddy up and look out for each other
• Always let someone you trust know where you'll be so they can help if something unexpected happens
• Acclimatise yourself
• Attend organised events

If you do get into trouble in the water, the RNLI recommends "Float to Live": lean back, extend your arms and legs, and resist the urge to thrash around - this helps you control your breathing until the effects of cold-water shock pass, so you can then call for help or swim to safety [16].

Have we convinced you to give it a go?
 

Before you get started with your new hobby, why not measure your fitness starting point with one of our Sports Performance Blood Tests? Our Fitness Blood Test is perfect for establishing your baseline level of health so that you can track improvements as you progress. It includes tests for liver function and cholesterol as well as for energy, muscle, inflammation, and vitamins.

References

1. The open water community has doubled since 2017 - Outdoor Swimmer Magazine. [cited 6 Aug 2026]. 
2. Hjorth P, Sikjær MG, Løkke A, Jørgensen AM, Jørgensen N, Kaasgaard DM, et al. Cold water swimming as an add-on treatment for depression: a feasibility study. Nord J Psychiatry. 2023;77: 706–711. doi:10.1080/08039488.2023.2228290
3. Study to explore if outdoor swimming is helpful for depression after successful trial. In: University of Portsmouth [Internet]. 27 Mar 2024 [cited 6 Aug 2026]. 
4. Peres D, Prati C, Mourot L, Demartino AM, Sagawa Y, Tordi N. Effects of an Exercise Program and Cold-Water Immersion Recovery in Patients with Rheumatoid Arthritis (RA): Feasibility Study. Int J Environ Res Public Health. 2023;20: 6128. doi:10.3390/ijerph20126128
5. Buijze GA, Jong HMYD, Kox M, Sande MG van de, Schaardenburg DV, Vugt RMV, et al. An add-on training program involving breathing exercises, cold exposure, and meditation attenuates inflammation and disease activity in axial spondyloarthritis – A proof of concept trial. PLOS ONE. 2019;14: e0225749. doi:10.1371/journal.pone.0225749
6. Wang Y, Li S, Zhang Y, Chen Y, Yan F, Han L, Ma Y. Heat and cold therapy reduce pain in patients with delayed onset muscle soreness: A systematic review and meta-analysis of 32 randomized controlled trials, 2021.doi:10.1016/j.ptsp.2021.01.004 [cited 6 Aug 2026]. 
7. Pioneering study examines cold water therapy’s potential to treat PTSD. In: Swansea University [Internet]. [cited 5 Aug 2026]. 
8. Romu T, Vavruch C, Dahlqvist-Leinhard O, Tallberg J, Dahlström N, Persson A, et al. A randomized trial of cold-exposure on energy expenditure and supraclavicular brown adipose tissue volume in humans. Metabolism. 2016;65: 926–934. doi:10.1016/j.metabol.2016.03.012
9. Gibas-Dorna M, Chęcińska Z, Korek E, Kupsz J, Sowińska A, Krauss H. Cold Water Swimming Beneficially Modulates Insulin Sensitivity in Middle-Aged Individuals. J Aging Phys Act. 2016;24: 547–554. doi:10.1123/japa.2015-0222
10. Cold water swimming: is it bad for your heart? In: British Heart Foundation [Internet]. 31 May 2023 [cited 6 Aug 2026]. 
11. Espeland D, de Weerd L, Mercer JB. Health effects of voluntary exposure to cold water – a continuing subject of debate. International Journal of Circumpolar Health. 2022;81: 2111789. doi:10.1080/22423982.2022.2111789
12. Exercise. In: nhs.uk [Internet]. 25 Jan 2022 [cited 6 Aug 2026]. 
13. White GE, Wells GD. Cold-water immersion and other forms of cryotherapy: physiological changes potentially affecting recovery from high-intensity exercise. Extrem Physiol Med. 2013;2: 26. doi:10.1186/2046-7648-2-26
14. Wang Y, Li S, Zhang Y, Chen Y, Yan F, Han L, et al. Heat and cold therapy reduce pain in patients with delayed onset muscle soreness: A systematic review and meta-analysis of 32 randomized controlled trials. Phys Ther Sport. 2021;48: 177–187. doi:10.1016/j.ptsp.2021.01.004
15. Cold Water Shock – the Facts. In: Royal Life Saving Society UK ( RLSS UK ) [Internet]. 1 Apr 2019 [cited 6 Aug 2026]. 
16. RNLI Open Water Swimming Safety Advice And Tips. [cited 6 Aug 2026].