The bump on my fin normally would have meant nothing at all, except for the fact that I was in a pond and was not kicking at the moment. Whatever it was had hit me pretty hard, and my mind was calculating quickly just how big of a snapping turtle it may have been? That's when it exploded! The water that is, and directly behind me! Had I not been strapped into my float tube by my bungee corded apron, I may have launched myself completely out of the thing, and onto the nearby shore.