We have the imse vimse swim nappies at The Nappy Bucket (see sig) I have taken my DD swmming in these and poo hasn't been a problem but she hasn't done a huge one in them yet. They have won awards overseas apparently and are the only swim nappy approved by swimming pools over in EC apparently (this is the marketing the sent me anyway) I love them and they come in a good range of sizes esp for small bubs