1. The water mass at the deepest part of the water column. It is the densest water that is permitted to occupy that position by the regional topography. In the case of a basin, bottom water may be formed locally, or it may represent the densest water that has existed at sill depth in the recent past. 2. Water masses found at the bottom of ocean basins. The most important bottom waters of the World Ocean are Antarctic Bottom Water and Arctic Bottom Water. Baffin Bay Bottom Water has a salinity of 34. 49 and a temperature of −0. 4°C and is found in Baffin Bay below a depth of 1800 m; its low oxygen content of 3. 6 ml l−1 indicates slow water renewal. Japan Sea Bottom Water has a salinity of 34. 1 and a temperature of 0. 04°C; it is formed by winter convection in the northern Japan Sea and occupies the Japan Sea basins at depths below 2000 m.