underwater. I know people who have but I wouldn't. I also know a guy who changed his adjustments several times to get the right pitch. That's a little to adventurous for me but he saved a bunch of haul out money. I'm talking about a good old three blade prop with no buttons or add ons. anyone can do that with scuba or a hooka rig. In the old days I seem to remember doing it without breathing equipment but that's out of the question now.