@pidge32 you don't need to keep your ostomy appliance dry - its already waterproof. I swam on a masters swim team and did hour long workouts in the water without any problems with the ostomy pouch. I also did meets, so I would do a start from the block without any problems. I wear a snug one piece speedo to keep the bag from flopping around.

If you have an appliance that has tape, you might try wiping the tape with barrier wipe to "waterproof" it. I use 3M Medipore tape to picture frame my appliance before swimming because it doesn't have any tape and the edges get gummy.

I always suggest, if you are unsure how your appliance will do in the water, to fill the bathtub up and sit in it with water over your appliance. See how it does in the home environment.

I've been in and out of the water for up to 10 hours while scuba diving without trouble, and if I am going to be in the water that long I use SureSeal, which is a clear plastic tape made by Active Lifestyle Products https://alpglobal.com/

Here is an article on swimming that may get you started: https://connect.mayoclinic.org/blog/ostomy/newsfeed-post/swimming-with-an-ostomy/