Every movement the deep submergence vehicle (DSV) Alvin makes is recorded by computers on board the ship and on the DSV Alvin itself. This image from the Alvin's navigation shows the sub's track (in green) after a dive which was partially dedicated to photomosaicking. The close parallel lines are necessary to provide enough overlap in the photos to that they can be properly pieced together. Image courtesy of Expedition to the Deep Slope.
