Using the equation of continuity, computations of the vertical velocity distribution in the upper ocean were made from moored horizontal current measurements recorded for 3 month intervals near 0 degree , 110 degree W. A depth-averaged upwelling velocity of 2.0 x 10 super(-5) m s super(-1) was characteristic of the Equatorial Undercurrent (EUC). Below the undercurrent, the mean vertical motion was directed downward. In the EUC the nonlinear advection was comparable to the westward force of the prevailing southeasterly winds.