I would not doubt it. If you know the name of the island do a look up on Wikipedia or Google or Snopes and see if it's for real.
The Boundry Waters Canoe area is strange like that I know. The National Boundries run through islands. When we went up there in '97 we landed on 1 side of an island, walked about 100 yards and had to cross into Canada. They had a Mountie station set up with a customs office inside. You could just walk around the side of the office and skip Customs. If you came up after 6PM you were supposed to either camp on the US side or come back the next day and go through Customs.
I am SURE things are different NOW (post 9/11).
____________________ Revenge is a dish best served cold!