Three dimensional, direct numerical simulation of double-diffusive fingering instability in a sedimenting system. In this simulation, a layer of fine sediment (red = max sediment load, blue = no sediment) is placed over a salty layer. This setup is based on a sediment-laden fresh water river flowing along the surface as it reaches the ocean. The overall density gradient is stable (light fluid on top), however differences in the diffusion coefficient between the sediment and salinity cause an instability to develop. This instability is modified by the settling velocity of the sedimen