This is the USS Cobia, a WWII Submarine laid down in March 1943 in Groton, CT and launched November 28th, 1943. She had 6 war patrols, sinking 13 enemy ships and suffered only one casualty for the entire war, a 20mm gun loader hit by machine gun fire from an attacking surface vessel while on the surface.
In 1970, the Navy decommissioned Cobia and she was towed to Manitowoc to serve as an international memorial to submariners. In 1986, Cobia was incorporated as a part of the Manitowoc Maritime Museum, declared a National Historic Landmark, and placed on the National Register of Historic Places.