I've worn contact lens to water parks & pools my entire live. Never had a problem or lost one in those situations......The only time I lost a lens was one time I was walking down the street with my ex wife. A really hot girl walked by, I gave a quick look, and the lens popped out of my eye.
My ex never let me forget that one. And she was actually hotter than the girl I eyed up. She was a Marilyn Monroe look alike if there ever was one.