Cruise ships sail out of Boston in the warm weather months, so for the winter they have to move to another departure port. The move is called a "repositioning cruise". You can get on a repositioning cruise from Boston in the autumn each year. See the calendar of departures below.
Repositioning cruises are usually bargains, because one-way cruises aren't as popular as round-trips. Out of Boston you can take a cruise to a warm place like California, Puerto Rico or Florida. Spend a little extra time there, then fly home. What could be better than that?