The high latitude regions play a key role in regulating the marine biogeochemical cycling of barium (Ba) and the pre-formed Ba isotope compositions in the global ocean. In this study, we present 17 new depth profiles of dissolved Ba concentrations ([Ba]) and isotope compositions (δ 138 Ba) from the high latitude Atlantic, Pacific and Southern Oceans to trace the ventilation of deep waters in the Southern Ocean and their subsequent transport throughout the global ocean. Our data reveal how biogeochemical processes in the Southern Ocean generate distinct δ 138 Ba signatures of upper ocean water masses, and that large scale ocean circulation constrains the meridional gradient of δ 138 Ba distributions in the deep Atlantic Ocean. The significant increase in [Ba] of deep waters in the North Pacific is mainly achieved through dissolution of sinking particles which adds a δ 138 Ba signal comparable to the deep Pacific Ocean.