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.
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. It is the only Great Lake not to border the state of Michigan.
Major rivers draining into Lake Ontario include the Niagara River, Don River, Humber River, Trent River, Cataraqui River, Genesee River, Oswego River, Black River, Little Salmon River, and the Salmon River.
