There are several exclaves between the United States and Canada, including the entire state of Alaska (though the state can still be accessed by sea from the United States, except the small settlement of Hyder which is only accessible by road from British Columbia).
There are several detached regions between the United States and Canada, including the entire state of Alaska, which is still connected to the U.S. via sea but has a separate access point for the settlement of Hyder through road from British Columbia.