Known as the Queen of the Great Lakes, the icebreaker ship, the Mackinaw, was built in Toledo, Ohio in 1944 to help keep shipping in the Great Lakes open during the winter. The need for iron ore, limestone and coal (the ingredients need to produce steel) was very during World War II. The vessel was commissioned in 1941, just over a week after the attack on Pearl Harbor. However construction delays prevented its completion until 1944. It was in operation for 62 years, finally decommissioned in 2006. It has been a floating museum ever since. One of the museum's highlights is the overnight program, where young people can sleep on board to get a hands on experience about how the ship functioned and what life was like on board.