The iron mule number 678 waiting on the side of one of the locks, possibly Gatun Locks, on the Panama Canal. The photographer is on board a ship in the lock chamber looking up at the mule which is connected to the ship by means of a wire rope. The driver of the mule is in his cab and the flagman is standing by the cab. Another man is seating outside the rear cab lighting a cigarette and he has a folded newspaper in his back pocket.