Three-dimensional reconstruction of an acoustic image of the lower 40 m of two buoyant plumes discharging from adjacent black smoker vents at a depth of 2635 m on the East Pacific Rise near 21 deg N, 109 deg W, (5x5x5 m rectilinear grid). The image was made from a digital data set of acoustic backscattering information recorded with a specially modified submersible-mounted sonar system. The reconstructed image shows multiple zones of flow organization, coalescence of two plumes, and bending of the coalesced plumes in the direction of the prevailing oceanic current (north). The newly developed acoustic imaging technique is providing information on the volume and structure of hydrothermal plumes on a time scale suitable for determination of plume dynamics and monitoring.