A Lighthouse Crusie aboard Famous Soo Locks Boat Tours is a greaet way to experience the beauty of the St. Marys River. This fully narrated tour is four hours and begins by riding through the Soo Locks. The tour follows the St. Marys River al lthe way to the entrance to the largest freshwater lake in the world - Lake Superior. Explore the important waterway and pay attention to the variety of navigation markers which lead ships to the Soo Locks from Lake Superior.