Archaeologists are trying to unravel the mysteries of an "incredibly rare" and exceptional medieval shipwreck buried under an old arm of the Garonne river for 1,300 years. The thick, water-logged clay has preserved the organic materials of the ship, including some rope fittings. There is almost no surviving written history of chronicling the navigation methods of the period, so the survival of this shipwreck is a unique testimonial to naval design in early medieval France.