H. L. Hunley, also known as the Hunley, CSS H. L. Hunley, or CSS Hunley, was a submarine of the Confederate States of America that fought in the American Civil War. Hunley demonstrated the advantages and dangers of undersea warfare. She was the first combat submarine to sink a warship (USS Housatonic), although Hunley was not completely submerged and, following her attack, was lost along with her crew before she could return to base. Twenty-one crewmen died in the three sinkings of Hunley during her short career. She was named for her inventor, Horace Lawson Hunley, shortly after she was taken into government service under the control of the Confederate States Army at Charleston, South Carolina.
Hunley, nearly 40 ft (12 m) long, was built at Mobile, Alabama, and launched in July 1863.