The Twin Ports: Duluth-Superior Harbor Professional Review and Guide
"Duluth and Superior together called the “Twin Ports,” are the leading bulk cargo ports on the Great Lakes, with forty to forty-five million tons of cargo shipped each season, and total tonnage as high as seventy-five million tons in some years. Located at the westernmost edge of the Great Lakes—St. Lawrence Seaway System, the Twin Ports are the farthest inland seaport in the world, 2,342 miles from the Atlantic Ocean.
The Duluth-Superior Harbor has approximately 17 miles of channels, 45 miles of frontage, and dozens of commercial docks, serving well over a 1,000 lake and ocean vessels every year, including some 200 vessels under foreign flags. The harbor provides great boat watching at a major international port. Just outside the harbor is a good surfing beach."