	The SS "St. Marys Challenger" is a freight-carrying vessel operating on the North American Great Lakes built in 1906. Originally an ore boat, she spent most of her career as a cement carrier when much larger ore boats became common. After a 107-year-long working career as a self-propelled boat, she was converted into a barge and paired with the tug "Prentiss Brown" as an integrated tug-barge. Before conversion, she was the oldest operating self-propelled lake freighter on the Great Lakes, as well as being one of the last freight-carrying vessels on the Great Lakes to be powered by steam engines.