The method presented accounts for three-dimensional effects when deghosting marine seismic data. The method relies on having second-order spatial derivatives in the cross-line direction available. The second-order cross-line derivative can be estimated directly or through indirect measurements of other wavefield quantities and by using wave-equation techniques to compute the desired term. The method preferably employs either a multicomponent streamer towed in the vicinity of the sea surface, a twin-streamer configuration near the sea-surface, or a configuration of three streamers that are separated either vertically or horizontally to estimate the second-order vertical derivative of pressure.