There have historically been two kinds of phenomena known as ghost ships -- the first, a mysterious apparition crewed by the souls of the damned, and the second, the sudden and unexplained disappearance of a ship's very real human crew. The Mary Celeste, an entirely normal American shipping vessel began as the latter when her crew vanished on a routine crossing of the Atlantic, but her story slowly morphed into the former over the next century. The true fate of the Mary Celeste's crew is likely far more mundane and far more disturbing.