Longest artificial seaway

The St Lawrence Seaway is 304km 189miles in length along the New York State-Ontario border from Montreal to Lake Ontario. It enables ships up to 222m 728ft long and 8m 26ft 3in draught (some of which are of 26,400tonnes) to sail 3769km 2342miles from the North Atlantic up the St Lawrence estuary and across the Great Lakes to Duluth, Minnesota, USA. The project, begun in 1954, cost $470 million and was opened on 25 Apr 1959.