Hi Kristy!
The Caribbean Pirate Adventure Cruise is a 2-hour trip for children between the ages of 4 and 12. Normally offered at 9:30 am on Sunday, Tuesday and Friday. The cost as of January 9, 2010 is approx. $36 per child.
During the cruise kids will also be offered a snack like pretzels, goldfish, juice or water. This trip is for children only and adults will not go along on the adventure - instead you'll have a couple hours of relaxation while your son is having a blast!
To book a reservation, you can call 407-WDW-PLAY.
My two kids had the chance to experience a very similar cruise last year at Halloween time. They had a blast, and were so happy to get to have this adventure on their own!
If you'd like to join your son on an adventure, another option would be the Pirates and Pals Fireworks Voyage. This boat excursion leaves from the Contemporary Resort, and gives you a great vantage point to view the Wishes fireworks from the Magic Kingdom. Along the way you may even run into a character or two. If this sounds like fun, you can read more about it
here.
Have a great trip!