We've done this pirate cruise the last 4 years with the kids' preschool. They have lots of fun attacking a pirate and stealing his treasure, corny pirate jokes and even a meet and greet with some lobsters and crabs! The kids also get their face painted, a pirate hat and their share of the treasure! The pirate cruise sails around Plymouth Harbor and lasts about an hour and is $18 per person. It's recommended for ages 4-11.  I'm not sure when the pirate cruises run since we've gone with a school and I'm sure reservations are required.