Here's a great-looking resource for adults who would still like to be able to swim or take arthritis fitness classes, but are afraid to do so because of possible "accidents."
Take a look at this swim diaper
There are others on the market, as well. Here are a few more links.
The Netti Combo
and Discovery Trekking Outfitters has one, too.
We've not tried any of these yet, but if you have and have any comments, I'd love to hear them.