I had a friend do a cruise wedding and it was a blast. Just call up one of the cruise lines you like and they have a planner that will help you. Also you have to get married before the boat leaves the dock to make it legal. That is even better because you and your guests get to go on the boat before all the other passengers. We had over 50 people go to this wedding so we got a group block rate and some free happy hours.
I've heard most destination weddings are done through special packages - saves a LOT on planning and details!
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