Visit a real functioning Lightship! Lightships are floating lighthouses that are anchored in areas where it was too deep, expensive, or impractical to construct a lighthouse. Lightships displayed a light at the top of a mast and, in areas of fog, also sounded a fog signal and radio beacon. The Huron Lightship sounded her fog horn signal in 3 second blasts every 30 seconds and was known locally as “Old B.O.” because of the familiar sound her horn made. The HURON Lightship was the last operating lightship on the Great Lakes, and served for over 50 years when she was retired in 1970, and was made a National Historic Landmark in 1990. Open for tours on weekends in Spring and Fall, and Daily from June 10 to September 2.