A current-measuring instrument employing the transmission of high-frequency acoustic signals in water. The current is determined by a Doppler shift in the backscatter echo from plankton, suspended sediment, and bubbles, all assumed to be moving with the mean speed of the water. Time gating circuitry is employed, which uses differences in travel time to divide the water column into range intervals called bins. The bin determinations allow development of a profile of current speed and direction over the entire water column. The ADCP can be deployed from a moving vessel, towing platform, buoy, or bottom-mounted platform. In the latter configuration, it is nonobtrusive in the water column and thus can be deployed in shipping channels.