In this project, the PI's will continue and complete a study of the general circulation in the tropical Atlantic using subsurface acoustic floats. 44 neutrally buoyant SOFAR floats were launched in early 1989, 14 at 800m, 15 at 1800m, and 15 at 3600m, corresponding respectively to layers of Antarctic Intermediate Water and Upper and Lower North Atlantic Deep Water. The array of 6 listening stations will be recovered in late 1992, resulting in a 3.5 year data set describing the Lagrangian characteristics of the flow in these important water masses.