SOUTH CAROLINA: After the Confederate submarine Hunley attacked USS Housatonic in 1864, the sub sank mysteriously, killing all eight of its crew. Experts have long wondered why the vessel went down, and some now believe it may have been due to a disabled air circulation system. New research suggests that the system of snorkel tubes and rubber hoses that pumped fresh air into the vessel while it remained submerged had been dismantled, perhaps contributing to the sub’s fate.