Disclaimer: even though we have been using this for almost three months, we have not had to deal with a poopy swim diaper, so I can't say anything about it's ability to hold in poop, but it seems like it would do a great job, and I am not worried about the day it will happen.

This is a well-made basic swim diaper.  The snaps on the side make for easy on and off, though not too easy - it definitely stays on during an active swim lesson and crawling around the kid's wading play area.  We recently bought some swim trunks to pull over it for some added cuteness, but this swim diaper can be used by itself with no worries.  A bit of warning, since it is meant to get wet, it is only lightly padded in the pee zone, and so if your baby pees more than just a little bit while you are holding him/her, you will get wet...  We wash this with our cloth diapers, and hang to dry, and after almost three months of weekly swim lessons it still looks as new as the day we got it.