On a boat
If you can get to a nearby port, it may be worth ditching airfare and considering a cruise. Travelocity's Shaw says being flexible about your travel dates, vessel and ports of call can yield the most substantial savings.
For example, Royal Caribbean's Enchantment of the Seas has deals for nine-night, round-trip Eastern Caribbean cruises that start at roughly $100 per person, per night. The deal includes 15% offshore excursions during stops in St. Thomas, San Juan and the Dominican Republic. But if you don't live near the ship's departure site in Baltimore, it likely won't be worth your while.