The week before: Ooh the weather looks nice this weekend, good time to try out a 10K. Perfect, the Big Brutal Swim allows entries on the day, so people like me who aren’t organised months in advance can take part!

The day before: Hmm what shall I eat? 10K is going to require some energy. Pasta, protein & cake today & for breakfast tomorrow morning methinks.

The morning of the swim: Pasta for breakfast? What was I thinking? Oh well, too late now, I’ll have some raisin & banana cookies on the drive to Llanberis to make up for it. So, it’s going to be 8 laps of 1.25K each. How am I going to count 8 laps?? I can’t remember where we are on anything more than 100m in the pool. It’s going to be embarrassing if I get out a lap too early. Or do an extra lap. We have to exit the water after every 2 laps, so if I lay out 3 gel packs, I can take 1 every 2 laps and keep count of how many laps I’ve done. Cunning plan.

The mass start: I haven’t done one of these before. I wonder if everyone who has swum to the front is actually quite fast. And we’re off. Lots of thrashing. I seem to be going past quite a few people. Turns out not everyone who lined up at the front is a fast swimmer.

The 1st 2.5K: Reach, reach, long and smooth. Quite a bit of argy bargy turning round the buoys. I have no idea why this person is insisting on swimming right next to me. I’m sure she thinks she’s following the right line, but I’m swimming straight and she keeps whacking into me. I’ll stay a head in front to avoid her. Which flavour gel shall I have after lap 2?

2.5 – 5K: Interesting, I thought I was quite quick slurping up that gel, but the swimmers who exited with me didn’t stop and are now 40m ahead. I wonder if I can catch them. I feel like I could swim the Channel. That gel might have had a bit of caffeine in it. Reach, reach, power through the stroke. I don’t want to put too much effort in too early, maybe they are doing 5K and not 10. What’s that paddler doing in front of me, pointing in the other direction? Oh, the next buoy is 90 degrees to the left? I see it now, thank you! Bugger, that’s an extra 80m to swim to get back on course. Did I bring cake for afterwards? Swimming with a wetsuit is great, I don’t even have to bother to use my legs at all! Shoulder above elbow, above wrist, above hand. Nearly lost my goggles with that shove – calm down everyone, we’re not in the Olympics. Shall I have a gel this time or not bother?

5 – 7.5K: Mmm I’m glad I had that gel, I feel like a dolphin! Not many people left around. Much prefer swimming in peace. Such a nice lake. Might visit the slate museum after this. I bet they have a good café. With cake. What the heck is that?! Oh, pondweed. Reach, reach, long, long. Ooh that’s a nice cozzie she’s got on. I must ask her later which make it is. Shall I go for another gel or just hop straight back in?

7.5 – 10K: A bit of stomach cramp is probably worth the extra energy that gel gave me. Reach, reach, need to put some power into these last 2 laps. I reckon I could manage Windermere next. Look down, legs up. Nice slice of cake after this. And pizza. And wine when I get home. If I can lift a glass up – I think my arm is going to drop off if I do this much longer. Is this the last lap or have I got another one? Oh god, I can’t remember if I got out 1 or 2 laps ago. Is it worse to get out now and be sent back in, or just go round again even if it’s an extra lap? I’ll swim up to the exit, keep my goggles on and ask them whether I’ve finished. It’s pretty shallow, I’ve just swum past someone’s ankles. “Hi, I think I’ve finished, but I can’t remember how many laps I’ve done. Emma Sharpe. 10K. I have finished? Ooh yes, I’ll have some flapjack, thank you!”