USCGC Mackinaw (WLBB-30) is a 240-foot (73 m) multi-purpose vessel with a primary mission as a heavy icebreaker specifically built for operations on the North American Great Lakes for the United States Coast Guard. IMO number: 9271054. Her larger precursor, the USCGC Mackinaw (WAGB-83), IMO number 6119534, had a 62-year career on the same waters prior to being decommissioned on June 10, 2006, and turned into a museum ship docked in Mackinaw City, Michigan.