A few years ago I thought people who swam in winter were completely insane. Why would anyone voluntarily jump into freezing water when you could stay warm and cozy indoors? Then I tried it. And like many things in life, my opinion changed completely once I actually experienced it myself.
Winter swimming—swimming in water below 5°C or during winter months has become surprisingly popular. It's no longer just something done by a few eccentric Nordic people. These days you see groups of swimmers all over the world meeting at lakes, seas, and even city ponds to take the plunge. So what's the deal? Is it actually good for you, or just masochism dressed up as wellness?
After looking into research and talking to regular winter swimmers, I found the answer: it is both. There are real benefits, but also real risks that you absolutely need to understand before you start.
The Physical Stuff
The health benefits are actually pretty interesting. Regular cold water swimming seems to help with cardiovascular health—blood pressure, cholesterol, that sort of thing. One study tracked middle-aged swimmers through a winter season and found their triglyceride levels dropped and they had lower homocysteine (a marker for heart disease risk).
There's also something going on with insulin and metabolism. Some research with overweight swimmers showed improved insulin sensitivity, especially in women with lower body fat. Your body goes through some beneficial changes when you regularly stress it with cold water.
But what really surprised me were the stories from people with chronic pain. I've read multiple accounts of people who stopped taking painkillers completely after swimming regularly for a few months. The buoyancy of water means you can exercise without putting weight on joints, which is great if you're older or dealing with injuries. One person I talked to said their mobility improved so much they couldn't believe it.
The Mental Game
Here's where it gets really interesting. Almost everyone who swims regularly says the mental health benefits are the biggest thing. And the research backs this up.
There's a famous case of a 24-year-old woman with severe depression who started swimming in cold water once a week. After some time, her symptoms reduced so much she stopped taking medication entirely. Now, I'm not saying throw away your antidepressants and jump in a lake—that would be irresponsible. But there's clearly something powerful happening. The theory is that cold water triggers a release of catecholamines (like norepinephrine) which activates your sympathetic nervous system and improves mood.
What really resonates with me though is the mindfulness aspect. When you're in freezing water, you cannot think about your work deadline or that argument you had yesterday. You're completely present, focused on your breathing, on keeping calm, on not panicking. It's forced mindfulness. Your brain literally cannot afford to wander. That's probably why so many people describe it as meditative.
And then there's the resilience building. Every single time you get in cold water, you're doing something uncomfortable. You're pushing past that voice in your head saying "this is crazy, get out." Over time, this builds mental toughness that spills over into other parts of life. If you can handle ice water at 6am, you can probably handle most things the day throws at you.
The Social Side
One thing I didn't expect is how social winter swimming is. Most people don't do this alone (and honestly, you shouldn't for safety reasons). Swimming groups form tight communities. There's something about standing on a beach together in winter, psyching each other up, that creates a bond.
The ritual matters too. It's not just the swim—it's the before and after. The nervous laughter before getting in. The collective gasps and shouts when you hit the water. And most importantly, the warming up afterwards with hot tea or coffee, wrapped in towels, sharing how it felt. For many people, these friendships become just as valuable as the swimming itself.
Does It Actually Boost Your Immune System?
This is complicated. A lot of cold water swimmers claim they get sick less often, and some research backs this up—studies show about 40% fewer colds and respiratory infections in regular swimmers. Short bursts of cold seem to activate your immune system and increase white blood cell counts.
But here's the catch: too much is bad. If you overdo it—swimming too long, too frequently, or in water that's too cold—you can actually suppress your immune system. The stress hormones that get released during cold exposure become a problem if they're constantly elevated. It's about finding the sweet spot: regular enough to get benefits, but not so much that you're chronically stressing your body.
The Risks Are Real
Okay, now the serious part. People die from cold water swimming. Not often, but it happens. And if you don't understand the risks, you could be one of them.
Cold Shock Can Kill You
The most dangerous moment is the first minute. When you hit cold water, your body has an involuntary response: you gasp, hyperventilate, and lose control of your breathing. This is called cold shock response, and it peaks around 30 seconds after you get in. If you're not prepared for this, you can inhale water and drown. Even experienced swimmers are at risk.
This is why you absolutely cannot just jump into ice water one day on a whim. You need to adapt gradually. Start swimming in autumn and keep going as the temperature drops. Your body will slowly build resistance to the cold shock. But if you skip this step and go straight to freezing water? You're playing with your life.
Hypothermia
After you survive the first minute, the next danger is hypothermia. Your core body temperature starts dropping from 37°C and keeps going down the longer you stay in. The tricky part is you might feel fine while it's happening. Your body lies to you.
How long you can stay in depends on a lot of things: your body fat, how hard you're swimming, the exact water temperature, your level of adaptation. Some research suggests swimming at about 70% effort helps maintain temperature in 10°C water, but colder than that and all bets are off. Everyone has a limit, and you need to learn yours through experience—cautiously.
Your Heart Might Not Like It
When you hit cold water, your cardiovascular system goes a bit crazy. Heart rate spikes, blood pressure shoots up, blood vessels constrict. For most healthy people, this is fine. But if you have any underlying heart issues—even ones you don't know about—this can trigger arrhythmias or worse.
There's this thing called "autonomic conflict" where your nervous system basically gets confused by the cold and sends conflicting signals. For people with certain conditions (Long-QT syndrome, coronary artery disease, heart muscle problems), this can be fatal. There have been deaths during official ice swimming competitions, even among experienced swimmers who passed medical screenings. If you're over 40 or have any cardiovascular risk factors, get checked by a doctor before you start.
Where You Swim Matters
I've tried both lake swimming and sea swimming, and they're quite different experiences. Lakes and lochs are usually calmer and more predictable than the sea. You can see the boundaries, there are multiple exit points, and there's no waves or currents to worry about. This makes them psychologically easier—you feel more in control.
Plus, swimming in a lake surrounded by trees and mountains gives you that combined nature experience (blue space and green space together), which studies show is more restorative than either alone. It feels peaceful in a different way than ocean swimming.
That said, freshwater has its own issues. Blue-green algae can be a problem in warmer months, and water quality varies a lot depending on the lake. The sea might be rougher, but it's also more consistent in some ways. Bottom line: know your swimming spot and check conditions before you go.
How to Do This Safely
If you want to try winter swimming, here's what you need to know:
Start in autumn. Don't wait for winter. Begin swimming when the water is still relatively warm and keep going as it gets colder. Your body needs time to adapt. Skipping this step is dangerous.
Learn your limits. Pay attention to what your body tells you. After enough swims, you'll develop a sense for when it's time to get out. This is a skill that builds with experience. Don't ignore the signals.
Choose your spot carefully. Pick locations with multiple exit points. Swim with other people whenever possible. Have someone on shore who can help if needed. This isn't the time to be a lone wolf.
Prepare for after. Have dry clothes, warm drinks, and shelter ready before you get in. The warming up process is just as important as the swim itself. Don't skip this.
See a doctor. Especially if you're over 40 or have any health issues. The cardiovascular stress is real, and you need to know if your heart can handle it.
My Take
After looking at all the research and talking to regular swimmers, I think winter swimming can be genuinely beneficial. The mental health improvements seem particularly strong, and the physical benefits are real too. The social aspect is a nice bonus.
But—and this is important—it's not safe by default. You can die from this. The difference between a healthy practice and a dangerous one comes down to preparation, gradual adaptation, and respecting your limits.
If you approach it thoughtfully and carefully, winter swimming can be transformative. But if you treat it casually, you're taking real risks. The water doesn't care about your intentions.
So if you're thinking about trying it: do your research, start slow, swim with others, and listen to your body. The cold water will still be there tomorrow.
Based on research from:
Knechtle, B., et al. (2020). Cold Water Swimming—Benefits and Risks: A Narrative Review. International Journal of Environmental Research and Public Health.
McDougall, C.W., et al. (2022). Freshwater Wild Swimming, Health and Well-Being: Understanding the Importance of Place and Risk. Sustainability.