Sixty years ago today, the first cargo ship began sailing the 2,300-mile length of the Great Lakes St Lawrence Seaway System, the world’s largest inland waterway, which connects the Atlantic Ocean with the western tip of Lake Superior. Traffic is no longer what it was at its height in the mid-1970s, but the seaway remains an important waterway, and one increasingly used by pleasure craft. I travelled part of it last autumn on a cruise ship, the Canadian Empress, for Telegraph Travel.