of hardwood. The mechanical property study on Vasa oak showed that the longitudinal tensile strength is severely reduced in several regions of the ship, and that the reduction correlates with reduced average molecular weight of the holocellulose. This could not have been foreseen without a thorough mechanical and chemical investigation, since the Vasa wood (with exception from the bacterially degraded surface regions) is morphologically intact and with a micro-structure comparable to that of recent oak. The results can be used in the ongoing task of mapping the condition of the Vasa wood.