Cold water swimming: the thrill of the chill

There are communities of adventurers who readily test their resilience to extreme cold. How do they do it?
17 March 2021

Interview with 

Anna Ploszajski, Materials Scientist


A swimmer in the sea.


As well as being a materials scientist, Anna Ploszajski is a cold water swimmer; she enjoys a regular dip in lakes and oceans that come close to freezing. And she's not alone - there are whole communities of such adventurers, who readily test their body's resilience to extreme temperatures. How do you become a cold water swimmer? Anna told Phil Sansom...

Anna - I live in central London and so for me, it's all about kind of reconnecting with nature, if that doesn't sound too hippie-ish! In the open water quite often it's just you, and so all you can hear is the sound of your arms making the bubbles as you do the strokes, and your own breathing; you can hear the birds around you... it's a very, very different environment for swimming.

Phil - It's maybe a stupid question, but it must get really cold, right?

Anna - It can get pretty chilly, yep, especially here in the UK.

Phil - Down to what, do you think?

Anna - The coldest I've been in is about one and a half degrees, which was in a small tarn halfway up a mountain in the Lake District.

Phil - Isn't that dangerous?

Anna - Yes. It would be dangerous if you went about it in the wrong way, of course. The way to acclimatise for swimmers is to get in regularly and get in while it is getting colder throughout the year, so while the autumn and the winter is starting. To be honest, it never feels good... what I mean is it would always feel cold, it will always feel shocking, you'll always feel nervous beforehand, but it becomes easier to overcome those types of negative feelings the more you do it and the more you realise it is going to be okay.

Phil - So do you think you feel the cold less - or you're just used to feeling the cold, you know what to expect, and you can handle it better?

Anna - I would say both. So there's the psychological element of getting in and getting cold, and that's the learned stuff, but there is definitely an uncontrollable element that is purely physical. And that's the side that I think is where the climatisation really comes into its own. That is your body physically adapting to learning how to do this. The first few times you do it, it can be really quite upsetting!

Phil - Right, because if you put me in the sea, even on the hottest day at Brighton beach or something, I'd still probably do a little high-pitched scream and then I'd run out!

Anna - Do you know what? There's still a lot of high pitched screaming that goes on in the cold water swimming community. You're really not alone - it's quite a universal experience! Actually the impact comes after you get out again and the recovery stages. What's really dangerous is to have a hot shower as soon as you get out, or to jump into any kind of heated environment like a hot car. All of the blood at the surface of your skin is still at one and a half degrees; if the body suddenly thinks that it's warm then it will start circulating that blood very quickly, which means that you're getting very, very cold blood going straight to your core, and that is when hypothermia can really set in. And that can drop blood pressure and do all sorts of nasty things. So at the lido that I swim in North London, you quite often get people fainting in the showers because they've gone for a cold swim and then they've come out and their blood pressure has dropped.

Phil - Wow. If you do everything right, people take this to quite extremes, don't they? Because you hear about people swinging huge distances in actual ice water.

Anna - Yeah, absolutely. The phenomenon of the ice mile has become really popular in swimming circles recently - so that's swimming a mile in water that is under five degrees Celsius.


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