Samples were taken from eighteen individuals from differing decks within the ship. Carbon (δ13C) and nitrogen (δ15N) isotope ratios in bone collagen, and oxygen (δ18O) and carbon (δ13C) isotope ratios in enamel apatite of these individuals were measured in order to obtain information about their diets and origins. While the collagen δ13C and δ15N data are similar to other medieval populations, the δ18O data indicate that a significant proportion of the crew did not originate in Britain. These data are argued to suggest the presence of 33–60% of non-natives, possibly mercenaries and/or ‘prest’ men, amongst the crew. This, together with documentary evidence, is argued to lend weight to the suggestion that poor communication may well have contributed the fatal navigational manoeuvre which led to the ship's sinking.