I was out in my sunflower (11 foot sailboat, yellow, easy to see) and a few jetskiers had fun running full speed past me several times. Fortunately, they were far enough away that I couldn't smack them with my paddle, because I was mad enough to... Being a sailor, I'm incredibly conscious of the rules of the water - unfortunately, some powerboaters and most jetskiers don't have that respect of those rules...
Luckily, most (but too far from all) people use common sense and courtesy out on the water.