We are of on holiday next months DS will be 2 and we have yet to take him swimming but hopefully will get plenty of chance to while away, obviously he needs swim nappies but looking at trunks from M&S are they roomy enough for a nappy underneath ? www.marksandspencer.com/2-pack-chlorine-resistant-assorted-swim-shorts-1-7-years-/p/p22343378