Lake Champlain joining the US and Canada. Adarondack Mountains of NY on the west and Green Mountains of VT on the east. It spans 120 miles and is some 4 miles at the widest point. The northern part is river-like, the middle wide with bays and islands, and the south again is river like. A strategic waterway during the French and Indian War, the American Revolution and the War of 1812, Lake Champlain has shipwrecks and forts everywhere.