Forget about chasing manatees. Skip drenching sunbathers with a watery rooster tail from the rear of your personal watercraft. And don't even think of awakening Star Island residents with that wonderful buzzing sound. All that is kid stuff. You need to take Jet Skiing to a higher level. Get out there at the mouth of Government Cut and boogie with the big boys: the cruise ships, tugboats, and speedy outboards. In 1905, when dredgers carved out the shipping lane that today parallels the MacArthur Causeway, they had no idea they had created a formidable Jet Skiing arena. But these days things have taken a turn for the fast. There's always a lot of challenging chop where the cut meets the sea (cruise ships make relatively small, though jumpable, waves). And there's a steady supply of adoring fans on the ocean liners and fishing piers. Half the fun of Jet Skiing is showing off, right?