Pack your down jacket and leave your bikini behind if you’re game to experience one of the most adventurous segments of cruising: the cold-weather itinerary. But you don’t have to travel long and far — say, to the Arctic Circle or Antarctica — to feel the brisk temperatures turn your cheeks rosy; if it’s winter charm you’re after, the answer could be as nearby as a Rhine or Danube river cruise in November or December. Here are eight cold-weather cruises and how to book them for less.