To be rid of those awful and pricy disposable swim diapers. Bought this white one b/c it was plain and basic with no silly patterns. My 18 month old runs around in this without a proper swimsuit and looks just fine. I bought according to his size and it was a bit small with no growing room, so you might size up. I really like the fact that, if necessary, I can throw this thing in the washer with some bleach and be ready for the next day of swimming. And I've gotten 3 months of use out of it already when I would've only gotten 2 weeks with the same cost in swimmie throw aways. Oy!