Many folks go out and buy swim diapers. If you are a cloth diapering family - you do not need this extra expense. Most cloth diapers do double duty as swim diapers. I will speak to what I know best, LolliDoo™.
LolliDoo™ has a couple of options for swim diapers. Our Recycled Outties™ aka diaper covers, are perfect for swimming. The intention of a swim diaper is to contain messes NOT liquids. Any fleece or PUL diaper cover should work nicely in the pool.
LolliDoo™ eco-pockets™ are another viable swim diaper option. No need for Organic Absorbency Innies™ aka absorbency inserts. Again - the idea is to catch messes.
You can even use a LolliDoo™ Free Spirit as a swim diaper (hey if you want to spend $79 on a swim diaper I won't stop you).
When covering your little one's bum in the pool - keep in mind that the diaper still needs to be tight enough to contain messes and without the Innies™ sometimes you have to really tighten up the leg elastic. Cloth diapers, when used for swimming, can be comparable to disposables in trimness but unsurpassed when it comes to comfort.