I don't know how well they work UNDER the water, but I do know they are great for shooting fish that are IN the water. Especially when they come up and get trapped in puddles along the riverside after the river has gone down. Almost as easy as using dynamite in my buddy's pond. I always figured this was how the term watertable came about. "Using a shotgun to get the fish from the WATER onto the dinner TABLE." Whatta you guys think?