From gestrophic calculations the exchange of deep water from the Somali into the Arabian Basin through the Owen Fracture Zone has been estimated to be about 2 Sv, with a seasonal modulation of the same magnitude. After leaving the Fracture Zone, the flow bifurcates into a northern and a southern branch, each closely following the slope of the Carlsberg Ridge. The weaker vertical gradients of the hydrographic properties in the deep Arabian Basin are consistent with enhanced vertical mixing at the rugged topography over the Carlsberg Ridge. ¿ 1997 American Geophysical Union