Adirondack Region Most of upstate New York is dominated by the huge Adirondack Park, the biggest park in the continental U.S. The Adirondack Region is bordered by Canada to the north, Vermont to the east, and Lake Ontario to the west. The St. Lawrence River divides the land from Canada, and is the setting for the spectacular Thousand Islands. Most of this stunningly beautiful land is filled with breathtaking forests, sparkling rivers, vast wilderness, and the tallest mountains in New York. |  |