Smallest and easternmost of the Great Lakes of North America. Bounded by New York and Ontario, and with the U.S.-Canada border passing through it, the lake is roughly elliptical; its major axis, 193 mi (311 km) long, lies nearly east to west, and its greatest width is 53 mi (85 km). The Niagara River is the lake's main feeder. There are five islands at its eastern end, where the lake discharges into the St. Lawrence River near Kingston, Ont. The Welland Canal and the Niagara River connect it to Lake Erie to the southwest. It was visited by Samuel de Champlain in 1615; its early French name was Lac Frontenac. Ports on the lake include Toronto and Hamilton, Ont., and Rochester and Oswego, N.Y.
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This lake is the highest point of the Trent-Severn Waterway; from here, the waterway descends to Georgian Bay in the northwest, and to Lake Ontario in the southeast. Some claim that Balsam Lake, at 256.3 m (841') above sea level, is the highest point on Earth to which a boat can be navigated from sea level. However, navigable portions of the system formed by the Mississippi River and its tributaries are at elevations of over 305 m (1,000') above sea level.