Yes, I have done some underwater photography while snorkeling. This barracuda passed in front of me off Morningstar Beach, St. Thomas, USVI in 1993.
I used a Minolta Dual (underwater) camera, Kodachrome film and the camera's built in flash. I was a little hesitant to turn on the flash since these toothy, large fish (this one was about 5 feet long) are known to attack shiny objects. But, I was a lot younger in those days and less cautious!