We collected seismic data along 15 transects to characterize the geometry of a coastal aquifer in Bénin, West Africa, that is being contaminated by saltwater. We used standard high-resolution seismic methods to image the upper using a sledgehammer source and a 120-channel recording system. Three transects were processed with an iterative updating flow that includes prestack depth migration, residual moveout analysis, and reflection tomography, and the remaining 12 transects were processed with routine processing flows and poststack time migration. We identified one unconfined aquifer and three confined aquifers separated by reflective confining clay layers. Some transects showed areas of missing reflectors, which we interpreted as sand-filled channels that could provide potential high-permeability conduits for saltwater flow to the Godomey well field.