Cardiff swim coach completes 24-hour world record swim

Heathwood Swim’s Dave Tonge covered 55km in 24 hours for charity. 220's Tim Heming finds ou how he did it and what he learnt.

Cardiff coach breaks swim world record

It’s 9am on Saturday 12 June and the tired arms of Cardiff swim coach Dave Tonge complete the final strokes of an endless pool swim that started 24 hours earlier.


The 39-year-old ultra-endurance swimmer from Heathwood Swim has covered 55km, raised more than £6,500 for charity (and counting) and – once he’s had some sleep –will be looking forward to the ratification of a new world record. We caught up with him to find out how it went.

220: Hi Dave, the first question has to be, how are you feeling?

Not too bad. I’m a bit achy today with my shoulders, but the second-day DOMS will start tomorrow!

220: How challenging did you find the swim?

The first 12 hours were easy because I’d done plenty of 12-hour swims in training. But I got to 15 hours and it was tough. My team were tired too, and they were trying to motivate me and stay awake. I swam 55km and was holding an average of 2:20 per 100m, although I did showboat a little bit and went a bit faster at times.

220: Why did you decide to do it?

To raise money for Velindre Cancer Centre, my local hospital in Cardiff. My wife’s father had prostate cancer and was having treatment there. He’s thankfully recovered now.

[In Dave’s previous swim he raised £5,300 for NHS Charities Together.]

I was swimming every day during lockdown and was up to two and three hours a day. I increased it to 12-hour swims and did a couple of late evening swims so I was tired swimming the next day too.

I thought that if all the doctors and nurses can stay up at night doing their job and then be up with the family the following day, there’s no reason I can’t swim all day and all night. I’ve proved to myself that’s correct.

220: How does the world record aspect work?

The record is for the longest swim – by duration – in a wetsuit in an endless pool. Ahead of a challenge like this, you have to come up with a suggestion of how long you’ll need for feeding and bathroom breaks, and they’ll say if it’s going to be acceptable to set a new world record.

We agreed on 25min swim, 5min rest. There were a couple of moments I felt I could do with a little longer recovery, but that was how I broke it down and got through it.

220: Why did you choose to do it in a wetsuit?

I’ve been doing loads of aerobic swimming in the past year during the pandemic. I’ve been plodding in my pool in my wetsuit in colder water because I had the heating turned off.

Usually, it was at much faster speeds, but instead of the 20 degrees I’d been training at, we turned it up to 26 degrees, which is race temperature for swimming pools.

220: How did the fuelling strategy play out?

We had a paramedic team that were monitoring my blood sugar levels every three hours. I had my carbohydrate and electrolyte drink, but was also topping up with Soreen and flapjacks – lots of high sugar stuff. When they checked my blood sugar halfway through it was 11.7 [blood sugar readings for a normal, healthy individual will be between 4-8].

I just wasn’t burning the fuel that I was putting in. I was getting headaches and starting to hallucinate. I then didn’t eat for three hours and it was down to 7.1 and that’s where we kept it.

My heart rate throughout the whole event never went over 80 beats per minute. Even though I was a sprinter in competitive swimming, now I’m getting older, I’m better at the distance swimming, keeping the technique and staying relaxed.

It’s a really interesting topic. [Former Welsh international rugby players Dave coaches] Alfie (Gareth Thomas) and Shane Williams are good endurance athletes these days, but they were fast twitch, powerful guys on the rugby field, and initially got in the pool and were absolutely gassed.

220: What hurts?

In the 12-hour training swims, my speeds per 100m were 1:49, 1:59 and 2:20. Because I’m predominantly a unilateral breather to the right, the two faster ones left my left lat and obliques really sore.

My physio encouraged me to really work on breathing bilaterally to “balance out the pain afterwards!”

After 20 hours I was consciously trying to pull with a bad technique under the water so I didn’t work my back muscles too much! But I’m paying for it in my shoulders now!

220: How did you manage being in a wetsuit for 24 hours?

You’re in a better position in the water, but you’re also more restricted in your movements. I wear the Huub Varman, which is a brilliant suit. I’ve worn all of Huub’s different suits over the years. I hardly used any lube on my neck. I had a tiny bit of a rash on my Adam’s apple, but swimming in a wetsuit for that long you’d think you’d get a rash.

220: Who was on your support team?

My brother Dan Tonge and brother-in-law Matt Thomas who are both fellow Ironmen. My coaches, Ross Hosking, Hope Stanger and Dan Davies. One of my swimmers, Sorcha Kennedy. Paramedic Gavin Quinn and the physios from Abloc Physiotherapy in Cardiff. It took place at Jane Versey’s All Swim facility.

220: And you had an additional challenge in making it an official world record…

Guinness waits for verification from Official World Records, who are based in Barcelona. I had loads of sponsors on board to pay for the rights and getting the judges to fly over from Spain to monitor it.

The record attempt was postponed four times because of Covid. We kept putting it off, thinking they’d be able to fly until eventually they said they were happy for the record to go ahead if I had an official timing company and a proper camera crew to stream it live.

I asked Joe Thomas from the Cardiff Met sports broadcasting team to help. Joe is also doing his master’s dissertation on me and had been following my training. He streamed it live on YouTube.


The two judges sat up all night watching it from Barcelona and communicating with Joe. It was the first time they’d ever done something like that and I now have to put all the evidence together and send it to Guinness. It’ll be worth it in the end.