Raye's Mustard Mill & Museum: Started in 1900 with one mustard flavor used for canning sardines, Raye's is the only mustard mill in the United States to cold grind mustard by stone. (That means you never have to refrigerate the mustard, even after it has been opened.) Today Raye's makes more than 20 varieties of flavored mustards. Visitors to the museum can see the grinding in action and taste a number of different mustards. If your cruise doesn't offer a tour to Raye's, you'll find Raye's employees down by the dock offering free rides up to the mill. (Or you can walk there in about 20 minutes.)
Campobello Island: The true main attraction in the Eastport area is a couple of hours out of town (so make sure you have enough time in port). Campobello Island, home to Franklin D. Roosevelt's 34-room cottage and the only international park in the world (it's jointly run and operated by Canada and the United States), lies just across a one-mile wide strait. However, there's no direct route from Moose Island. Getting there requires a 45-minute drive to Lubec, Maine and then across the FDR Memorial Bridge to Campobello. Because Campobello Island is in New Brunswick, Canada, you'll have to go through Canadian immigration before getting onto the island. There are no taxis in town, so your only option is to rent a car. A ferry between Eastport and Deer Island and then from Deer Island to Campobello may resume in the summer of 2016, but that is yet undetermined.