Regardless, for swim diapers, I AM 100% cloth. Not only do they help eliminate landfill waste, they're a great deal. One reusable diaper will run you roughly the same cost as one package of disposables. When you swim as much as we do, they are FAR cheaper than disposables. I've tested 2 brands, results below.
iPlay reusable swim diaper
The iPlay comes in several sizes, based on pounds. They seemed to run fairly true to size. The 6month size says on their website it will accommodate babies up to 18lbs, and baby wore this until just past 12months, when she was about 18-19 pounds. That being said, it also wasn't too big when she was smaller. This is a good quality diaper, we never had trouble with solids leaking out at all. But, it is all one piece, with no ties/openings/etc. While this might be a pro in some people's book, I found it extremely difficult to get on and off. Especially once it was wet. And, even more so if baby did have an, ahem, solid in it. Add in the fact that you're generally somewhere such as a locker room, dock, etc and it can be quite the messy and frustrating experience. It is also more padded than other cloth swim diapers we've tried.
Comes in a variety of colors. My one gripe is that all the girls colors have ruffles on the butt. I don't know about you, but I still put a swimsuit over it, so the ruffles just add to the bulk (and stick out strangely from some suits). I settled for one girl one with ruffles and one 'boy' one that is very gender neutral. I would stick to the boys ones in the future, no ruffle, exact same cut.
I'm not sure how it would fare if baby peed in it while OUT of the water, as we never had the er, pleasure. If it does in fact hold in pee when baby is say, on your lap while in a boat, I would definitely rank it higher. However, I don't think this is the case.
-It works! Keeps solids out of the pool with no problem.
-It is mostly hidden under a swimsuit. Bulky, but doesn't stick out as much as others.
-One piece makes putting on, and especially taking off very difficult. Can be messy if diaper is dirty.
-Gets to be a little snug on chubbier thighs toward the top end of the weight limit. No adjustments available
Kushies reusable swim diaper
This diaper also comes in several sizes, based on pounds. However, this one has velcro and ties and is quite adjustable. The Kushies website boasts many great colors/prints, but good luck finding them for sale. (The Kushies website does do retail, but you can find better deals other places if you're willing to go for the few styles/colors offered). These seem to run a little small...or, more accurately, small around the waist, but tall. Currently baby is in the 14-25 pound size and is 20.5 pounds. The waist, since its adjustable still fits, but I guess I'd like it to be closer to 'closed'? There is quite a bit of velcro showing when it is tight on her, but technically, it fits. These are very well designed diapers, fully adjustable, easy on/off (even with a mess), and they were smart enough to put the "soft" part of the velcro facing out, as to not ruin swimsuits/clothes/etc that would rub on it.
While the waist on ours is just barely closing, when it is wet, it is VERY droopy. They seem to be a bit long/tall. The cut is a bit strange, with elastic around the legs, but then an extra piece that covers it. Looks cute when dry/no swimsuit over it, but stick out of the (girls) swimsuit a lot and kind of oddly.
-Cute patterns, if you can find them, several uni-sex patterns, good if you plan to use for more than one child.
-Adjustable with velcro/ties around waist.
-Fit is a bit strange--tall/saggy, sticks out of swimsuit
-Does not hold in pee (I don't know of any that do, but I still wish they did!) Makes boating/hanging out on the beach/dock/etc difficult. Or, messy at the very least.