I bought my son some Nexcare Tattoo Waterproof Bandages a few months ago, because every time he'd use regular bandaids, they'd fall off after getting them wet.
Alas, we don't have to worry about THAT anymore! Nexcare bandages are clear (unless you get an animated motif--we got Finding Nemo) and make a GREAT seal. Even if your child gets the wound area wet, the bandage will STAY ON. Plus, it's not bulky like Band-Aids--and it also lets the skin breathe.
Highly recommended if your child's band aids don't stay on or if you want waterproof bandages!