The closest ocean to Toronto is the Atlantic Ocean.
Toronto is located in the province of Ontario, Canada, and is situated near the Great Lakes. While the Great Lakes are freshwater lakes, the closest saltwater body is the Atlantic Ocean, which is accessible through the St. Lawrence River. To reach the Atlantic, one would typically travel south from Toronto through Ontario, enter Quebec, and follow the river until it flows into the ocean. The distance to the Atlantic Ocean is approximately 1,600 kilometers (about 1,000 miles) from Toronto, making it quite a journey, but it is still the nearest oceanic body in relation to the city.