Duluth, Minnesota Lakes Waterway and the Saint Lawrence Seaway. Duluth forms a metropolitan area with neighboring Superior, Wisconsin, called the Twin Ports. The cities share the Duluth–Superior harbor and together are the Great Lakes' largest port, transporting coal, iron ore (taconite), and grain. A tourist destination for the Midwest, Duluth features the United States' only all-freshwater aquarium, the Great Lakes Aquarium; the Aerial Lift Bridge, which spans the Duluth Ship Canal into the Duluth–Superior Harbor; and Minnesota Point (known locally as Park Point), the world's longest freshwater baymouth bar, spanning . The city is also the starting point for vehicle trips along
The Great Lakes Group provides linehandling assistance to vessels transiting the United States Army Corps of Engineers-administered and -operated Soo Locks at Sault Ste. Marie, Michigan on the St. Mary's River, the only water connection between Lake Superior and the other Great Lakes. The Soo Locks are located in the St. Mary's Rapids, where the water falls about 21 feet from the level of Lake Superior to the level of the lower lakes. Vessels must transit the Soo Locks en route to the principal ports of Duluth, Minnesota and Thunder Bay, Ontario and outbound to the sea. In 1999 Admiral Towing and Barge Company