I guess if you put this on right before you got into the pool, you might not notice that this diaper holds no urine at all, it doesn't even slow it down. I put the diaper on under my daughter's swim suit and then put her in the car seat to drive to the pool, thinking this would save time and fussing. Well, imagine my surprise when we got to the pool and my daughter's clothing and her car seat were DRENCHED in urine! I checked and the diaper was on properly, and as I was holding her she urinated again and now we were both soaked in her urine. So much for saving time and fuss. I had laundry to do for both of us and I also had to remove the car seat from the car to get the cover off and wash and dry it. I guess these will hold in a BM, as they seem very snug, but I won't be using these again and I won't recommend them. Oh, and although our daughter weighs only 28 pounds, the medium just barely fits her, it's supposed to fit up to 34 pounds.