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 American 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. Many of Ontario's most populous cities, including Toronto, Canada's most populous city, and Hamilton, are on the lake's northern or western shores. In the Huron language, the name Ontari'io means "Lake of Shining Waters". 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.

Where does the water from lake ontario go? OK. Let's think. My stream of consciousness:
To answer this question, we should know that: The last in the Great Lakes chain, Lake Ontario serves as the outlet to the Atlantic Ocean via the Saint Lawrence River. The answer is the Atlantic Ocean via the Saint Lawrence River.