Every year 7,000 to 10,000 ships use this free connection between Lake Superior and Lake Huron, which allows ships to traverse all the way from the Atlantic Ocean to the iron ore and grain ports of Minnesota. 

Lake Huron and Lake Superior are elevations, and the locks are like a water elevator that allowed ships to move between the two. Think of it as a man-made replacement for a waterfall, where a ship can move in either direction. As a spectator standing at the top of the locks, visitors are at the level of Lake Superior looking down at Lake Huron while steel doors hold back all the water of Lake Superior from flooding the bay. 

A visit to the locks is rich with history and beautiful architecture and a must-see for boat nerds who get an opportunity to see the 1000 foot ore boats close up. During Engineer Days, on the last weekend of June, visitors are allowed onto the locks for the closest views, though there is a viewing tower that is available any time during the shipping season. Commercial boat tours also allow visitors to experience the locks themselves.