Forget waterskiing and wakeboarding. Those are the watersports of yesteryear. This summer, try riding the surf on a wakeskate, hoverboarding across the Muskokas, or flying underwater with a hydrodynamic set of wings. Here are 7 new watersports—starting with the tamest to the most extreme—that you need to try. All you need is a little courage and a layer of sunscreen.