The subseafloor structure offshore western Canada was imaged using first-order water-layer multiples from oceanbottom seismometer ͑OBS͒ data and the results were compared to conventional imaging using primary reflections. This multiple-migration ͑mirror-imaging͒ method uses the downgoing pressure wavefield just above the seafloor, which is devoid of any primary reflections but consists of receiverside ghosts of these primary reflections. The mirror-imaging method employs a primaries-only Kirchhoff prestack depth migration algorithm to image the receiver ghosts. The additional travel path of the multiples through the water layer is accounted for by a simple manipulation of the velocity model and processing datum: the receivers lie not on the seabed but on a sea surface twice as high as the true water column. Migration results show that the multiple-migrated image provides a much broader illumination of the subsurface than is possible for conventional imaging using the primaries, especially for the very shallow reflections and sparse OBS spacing. The resulting image from mirror imaging has illumination comparable to the vertical incidence surface streamer ͑single-channel͒ reflection data.

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