We bought some swimmers from Big W that are the lycra swimmer material on the outisde & plastic stuff in the middle then something else on the inside (OMG how dodgy is that description). Anyway that aren't a nappy as such, but they keep everything in. They were in the baby section near the Huggies swim nappies and are in a clear palstic sleeve for storage with a blue label at the top.

ETA: just found out the brand is Fluffies.