Homeland Security cracks down on canoeistsIf you are a Canadian canoeing the wild river St. Croix on the New Brunswick and you capsize and struggle to the American side the DHS will be there to arrest you for illegal entry. This actually happened to a jet skier in the Niagara Gorge a few years back.
Heaven forbid if you try to use an American campsite like your parents did back in the 20th Century they will arrest you for illegal entry too, even if there is now way out of the area except back into the river.