Tucked neatly away on the border between New York's Adirondack and Thousand Islands regions, Sylvia Lake is the perfect Northern New York location for the annual family vacation. Sylvia Lake is a 324-acre lake on a tributary to the Oswegatchie River. For its small size, Sylvia Lake is very deep, reaching 140 feet in the central 'hole' near the middle. An area of wetlands near the inlet at the south end provides habitat for waterfowl including the elusive loon, symbol of northern lakes everywhere