when I was a young warthog, i subscribed to National Geographic World, a magazine for kids. all kindsa cool kid stuff in it. one thing that I learned is that sharks are attracted to shiny objects. (at least they were back in the late 70's or early 80's). when i swim in the ocean (which i try to do as infrequently as possible), I remain congisant of this tip and try to dress more like a seal than like a shiny fish.