Claim: Ontario contains The St. Lawrence River.

The Saint Lawrence River -LRB- Fleuve Saint-Laurent Tuscarora : Kahnawáʼkye ; Mohawk : Kaniatarowanenneh , meaning `` big waterway '' -RRB- is a large river in the middle latitudes of North America . The Saint Lawrence River flows in a roughly north-easterly direction , connecting the Great Lakes with the Atlantic Ocean and forming the primary drainage outflow of the Great Lakes Basin . It traverses the Canadian provinces of Quebec and Ontario , and is part of the international boundary between Ontario , Canada , and the U.S. state of New York . This river also provides the basis of the commercial Saint Lawrence Seaway .