The water movement in the world ocean is examined using a velocity field diagnostically derived from hydrographic and wind stress data. The movement of water is calculated numerically by tracking its constituent particles, and the attention is focused on where the water originates. The particle tracking indicates that deep water is formed not only in the North Atlantic and the Weddell Sea but also in the Ross Sea. The North Atlantic Deep Water contributes considerable volume to all the deep basins of the world ocean, while the Weddell Sea Deep Water (WSDW) tends to be confined to the southern region of the southern ocean. Similarly, the Ross Sea Deep Water (RSDW) does not flow northward in the present model because the Antarctic Circumpolar Current (ACC) penetrates sufficiently deep to carry the RSDW away to the South Atlantic. It is also found that the WSDW does not mix directly with the Circumpolar Water because of the South Scotia Ridge, but rather mixes with the water recirculating in the Weddell Gyre, which is supplied by the middepth water of the ACC in the Atlantic-Indian Basin. Water composition in 16 basins is summarized in the form of box diagrams of deep water exchange. ¿ American Geophysical Union 1992