saint lawrence seaway

noun

1. a series of channels, locks, and canals between Montreal and the mouth of Lake Ontario, a distance of 182 miles (293 km), enabling most deep-draft vessels to travel from the Atlantic Ocean, up the St. Lawrence River, to all the Great Lakes ports: developed jointly by the U.S. and Canada.

noun usually abbreviated to: St Lawrence Seaway

1. an inland waterway of North America, passing through the Great Lakes, the St Lawrence River, and connecting canals and locks: one of the most important waterways in the world. Length: 3993 km (2480 miles)