Huggies Little Swimmers, Swim Nappies, Size 5-6 - 33 Pants £12.75 / £12.11 via Subscribe and Save @ Amazon

I implore your forgiveness for peeing in the pool on multiple occasions as a kid.

My only excuse was that it was more efficient than getting out of the pool.

If you don't need so many then they're £4.25 for 11 at Morrisons and Ocado (works out about 2p more per nappy), or £4 at Savers and B&M (same price per nappy). Alternatively Boots have a 2 for £8 offer on these, so 22 for £8 which again is the same price per nappy as Amazon. I appreciate Amazon may be more convenient for many. (edited)