A theme cruise can help you dive deeper into a personal interest — from knitting to music and even a favorite TV show. (Yes, we're thinking of “The Walking Dead”-themed “Walker Stalker” cruise.) But other theme cruises take the concept of exploration at sea with like-minded fellow passengers further than others. Case in point: These five cruises celebrate edgy, unusual, possibly shocking themes ... not that we’re judging. Hey, whatever floats your boat, right?