In which I discover that swimming in a wetsuit is a rather different beast.
The lovely people at Speedo were kind enough to give me a wetsuit for my moment of swimming glory. It is a thing of beauty - it even has fin bits on the arms and pleasing stretches of gold neoprene.
But swimming in it took a bit of getting used to. First of all there was the ten-minute struggle to get it on (hello plastic bags over my feet, goodbye dignity!). Then there was the actual, you know, SWIMMING. South London's Brockwell Lido didn't know what had hit it. I picked a quiet lane so as not to annoy the honed and toned swimming machines ploughing up and down, and then started splashing around and whingeing.
It was tight around the neck. The water was cold on my face, but my forearms were warm. It was so BUOYANT (and I know that's its job) - my feet were splishing around on the water's surface. My chest hurt.
But a couple of sessions later it was feeling more and more normal. Sitting right at the top of the water meant I didn't have to roll as much to breathe. It felt like I was moving quicker, that it was easier to push more water past me. My legs being more buoyant meant I had a better position in the water.
After Hyde Park, I've got one other open water swimming event this season - a 1500m river swim in Marlow, Buckinghamshire. I'm nervous about doubling the distance, but I do know that my wetsuit will do me proud.