If you're hunting for a great cruise deal, you'll likely see "repositioning cruises" pop up among the lowest-priced sailings. But what exactly is a repositioning cruise? In the simplest terms, it's a sailing that relocates a cruise ship from one region to another, usually done seasonally. Since it doesn't make sense for cruise lines to keep their ships empty for the week or two it takes to travel between locations, they offer special fares to make the long cruises more enticing. We're talking 16-day cruises that cost $850 per person (or about $50 per day). There are some trade-offs, though, so before you commit to a repositioning cruise, here’s what to keep in mind.