Lake Ontario is the easternmost of the Great Lakes and is positioned at the base of the Niagara Falls. It is bordered by Ontario to the southwest, south and north, and New York to the south and southeast. Lake Ontario forms part of the international boundary between the United States and Canada. Its entire northern shore is in the province of Ontario, and its southern shore from Youngstown eastward is in the State of New York. Except for Rochester, NY, Lake Ontario’s southern U.S. shore has little major development, but Canada’s industrial centers of Hamilton and Toronto occupy its northwestern shore.

The lake is almost 175 nm long and 46 nm wide at its broadest point, with lake depths ranging from 100 to 800 feet offshore. It has an average depth of about 283 feet and covers 7,340 square miles, making it the smallest of the Lakes, yet one of the deepest, second only to Lake Superior. Its 620-mile shoreline encompasses rocky shores, sandy beaches, marshland, cliffs and forests, together with major metropolitan cities, industrial centers and quaint ports.