I live in Florida and swim a lot... in the salt water Gulf of Mexico and in chlorine swimming pools and water parks. I just wear my usual, everyday Coloplast Assura Extended Wear wafer and pouch, put on a one-piece with a skirt
and go swimming!
I was amazed the first time I went swimming in a pool, and the wafer actually stayed on. I was expecting it to fall off as soon as I took my bathing suit off, but it held it's seal perfectly. That was 5 years ago, and I've never had a problem since.
Everyone is different, and what works for me might not work for you, so you just have to try out different wafers and products to see what works best for you. You could always test them out in your bathtub at home to make sure it's going to hold it's seal under water before you go out swimming in public.
Once you find the product that works for you, go out there and have fun!
Dx'd Crohn's in '99 at age 28. Proctocolectomy and permanent ileostomy in '06.
Disease-free and medicine-free since surgery and very thankful to be healthy again.