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Why I Swim - Thirza Mulder

9 July 2021. Nearly 20 years after my last proper outdoor swim, I glide into a natural, 25m swimming pond, not too far from home, surrounded by flowering plants, bird song from the trees overhead. I need one lap to get used to the sensation, smell, temperature and sounds again, and then I just grin and go. When I get out, get changed and chat with the owner, I can’t stop my tears. I have had no idea I missed outdoor swimming so, so much!

Woman walking out into the water

When I was a child, growing up in the Netherlands, the local outdoor pool was open from mid April until the first week of September, and for as long as I can remember the whole family had a season pass. From a very young age, my sister and I were allowed to cycle the ten minutes to the pool, sandwiches, apple and bottle of water in the bag, and we would spent days on end in the water. If we weren’t in the pool, we went to a nearby lake, or to the sea, all on our bikes! And at home the paddling pool was usually up and ready for action, whenever the weather was nice.

Once I became a teenager and my never ending journey being overweight gained momentum, swimming in a pool no longer held its attraction. Open water swimming, yes, but much less frequent, and slowly I lost touch with the open water.

Long shot of the water with a few heads bobbing the distance

When Paul, my husband, and I moved to Northern Ireland in 2003, the only swimming places I visited were the local pool with our wee toddlers in tow and occasional a little paddling pool at a beautiful nature reserve at Lough Neagh about 40 minutes drive away (little did I know that that scary choppy lake would be one of my regular swimming spots 15 years on!). I began to hate the indoor swimming pool: it was always too smelly, too noisy, too hot and too cold at the same time, and I always seemed to end up with a head cold. Whenever I did see a place that would be perfect for outdoor swimming, it would be reserved for fishing. I gave up.

When I made a decision and decided to drastically change to a healthier diet, I also started running, gentle at first with C25K, more intense later, and finishing with a Belfast Marathon in 2013! When an injury threw a permanent spanner in those works, I started walking more. I love going to the Mournes and Mourlough beach for walks, but even on the beach, I would not really be tempted to go into the water (have to wear bathing suit? get wet? get sandy? pfff!). Walking was it for me.

In 2012 our eldest was diagnosed with leukaemia at 15 years old, life was turned upside down. He first spent five weeks at the Royal Belfast Hospital for Sick Children for initial treatment, coping with a central line, chemo, regular doses of pills of all kinds, and being thrown in at the deep end. He seemed to take most of this in his stride, throwing himself into his art projects and soon the room was the brightest and arty-est of them all on the ward.

Soon after admission he received his first visit from Helen from Cancer Fund for Children (CFFC) Cancer Specialist Support Worker. The CFFC support workers come onto the ward and spent a couple of hours with young patients and help them to take their mind of things, by doing art, crafts, watch a movie, listen to music, chat about trivial stuff, or the most important stuff. Those hours soon became something Hendrikje looked forward to the most.

Once home CFFC support worker Vanessa took over, and took Hendrikje to the cinema during quiet hours, and charity shopping, made mocktails in the kitchen, cooked, crafted and more. We as a family were also supported by CFFC: we received fuel grants towards petrol and heating oil, we spent time as a family at Daisy Lodge (Newcastle); Hendrikje and his siblings took part in residential stays at Narnia (a beautiful log cabin behind Daisy Lodge) and meet with peers who were going through the same experiences, Hendrikje was given the opportunity to take part in a youth conference and a sailing weekend, we sang in the CFFC Care Free Choir, where patients, parents, sibling, grandparents, carers, staff members and anyone who is affected by childhood cancer gets the chance to come together fortnightly to sing.

During the 2 and a half years of treatment (treatment finished July 2020 and Hendrikje is still in remission!) I took part in a number of fundraising challenges for Cancer Fund for Children, all hikes. In 2020-2021, we celebrate our 25th wedding anniversary, Hendrikje’s 18th and my 50th birthday, so I wanted to do something big in lieu of big parties. I planned a walk from home to Murlough Beach, a walk of six days through rural Northern Ireland to the beach near CFFC Daisy Lodge. Training was going well, until my old runner’s injury started playing up again and an x-ray showed early stage arthritis in the knee. There was no way I was going to risk further damage by undertaking such a long walk, so I had to come up with something equally big that did not involve walking or running…. Should I, could I start swimming again? Doubts where plentiful: where do I find places to swim, what if you are not allowed to swim, what if I have to drive long distances to get there? What kind of challenge should I do?!

First things first: go for that all important first swim in. A local family whose youngest was at school with our kids, and sadly passed away with cancer at the start of lockdown, agreed to let me have a swim in their natural swimming pond. As mentioned at the start, it was bliss, and the decision to do an open water challenge instead was easily made.

 On 10th October 2021 I started an open water dunk challenge, dunking 93 times before my 50th birthday on 1st March 2022, each dunk representing one year of the anniversaries we are celebrating during that time: 25th wedding anniversary, 18th birthday and 50th birthday!

I am absolutely loving the swimming, the company, the support and the amazing places available to swim in Northern Ireland, once you know where to look! The fact that this re-found love raises money for a well-loved charity is the icing on the cake! The sensation of the cold water, the sound of water lapping around you, the views across the sea, the lake, mountains, hills, farms, it is all envigorating and ensures a silly grin on my face for long after coming out of the water. I joke I now have a teeth-ometer: the more teeth I show (or even some gums), the better the dunk!
Group of people in their swimming gear next to a sign about the charity swim

I am very grateful for Swim Feral for sponsoring the challenge with a yellow Turtleback bag, which has already made travelling, changing (and getting noticed ;-) ) so much easier. Hopefully I will be able to go off the beaten track at some point for dunks with it as well.

For those wishing to donate, please go to 

For those want to participate in the dunks, please join the fundraiser Facebook group at, to keep up to date on dates and places. If you run a swimming group in Northern Ireland (formal or informal) and would like to host a dunk, send me a message!



Our Why I Swim project aims to give voice to our untold swim stories and strengthen our fantastic community. If you would like to share your story, drop us an email at


If you are new to outdoor swimming and feel inspired to give it a go, please ensure you do so safely. 

Firstly, have a read of our tips for winter swimming here and familiarise yourself with what's useful to have in your wild swim kit.

We would strongly advise trying out your first swim with an experienced cold water swimmer until you are completely confident of your own abilities. 

The Outdoor Swimming Society has a great list of local swimming groups which is well worth checking out and a quick search on Facebook should provide results.

And if you have any questions, pop a post in the Swim Feral Facebook page and our fantastic community of swimmers will be sure to help. 

Happy swimming xx



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