I have had my colostomy for one year. I have traveled extensively - several trips around the US - and to France and Mexico. I have done a lot of swimming in pools and in the ocean, and I get in our hot tub at home quite often.
I also use the tape barriers that are available from Coloplast. Sometimes I leave them on all week, especially if traveling. They work great. Just gives me additional confidence. I use a two-piece locking pouch system from Coloplast which I LOVE.
Before my first vacation trip, I got my swimsuits out, tried them on, and threw the ones where you could tell I had a colostomy in the charity pile. BTW, I also did this with all my other things - sundresses, t-shirts, blouses, pants, etc. One time and done. I normally wore loose and long tops so there wasn't much I had to give up.
I don't wear anything special when swimming, just my suit. I've never had a problem, even in really rough waves.
My approach has been to not limit myself. Whatever I did before, I will continue to do even if I have to find a solution. So far, this has been easy but it's much easier now that I'm done with chemo and I know my cycles. When I recently had to attend a couple of conferences and speak, I made sure to eat a very bland diet for a couple of days before (total bummer while I was in Cannes and Monte Carlo), but it was what I had to do to be in front of a lot of people in an auditorium with a microphone attached to my lapel -- Yikes! But it was fine.
I have only been stopped one time in airport screening, and it was by a young woman who asked if I had something in my pocket. I said, "No, I have an ostomy." She said, "Oh, OK. I had one for about six months when I was younger but was able to reverse it." What? I was shocked that the one time I was stopped was by someone who didn't even bat an eye.
Watch your diet the day before you plan to go swimming, find some barrier tape if you can, and have fun!