Cruises: quiet jaunts around the world for the respected and respectably retired. Except these guys didn't get the memo. Come aboad a cruise ship with a difference: for four days, 3000 revellers - aged between one and 70 upwards - and 60 heavy metal bands will cruise the Caribbean ocean. First off though, a launch party at Miami Beach. Welcome to the heaviest, most head-banging cruise of all time.