Lake Ontario is one of the five Great Lakes of North America. It is surrounded on the north, west, and southwest by the Canadian province of Ontario, and on the south and east by the U.S. state of New York, whose water boundaries meet in the middle of the lake. Ontario, Canada's most populous province, was named for the lake.
The Canadian cities of Toronto, Kingston, and Hamilton are located on the lake's northern and western shorelines, while the American city of Rochester is located on the south shore. In the Huron language, the name Ontarí'io means "great lake". Its primary inlet is the Niagara River from Lake Erie. The last in the Great Lakes chain, Lake Ontario serves as the outlet to the Atlantic Ocean via the Saint Lawrence River, comprising the eastern end of the Saint Lawrence Seaway. The Moses-Saunders Power Dam regulates the water level of the lake.
Lake Ontario is the only Great Lake not to border the state of Michigan.