Numerous geographical similarities exist between Plato's descriptions of Atlantis and a paleoisland (Spartel) in the western Straits of Gibraltar. The dialogues recount a catastrophic event that submerged the island ca. 11.6 ka in a single day and night, due to violent earthquakes and floods. This sudden destruction is consistent with a great earthquake (M > 8.5) and tsunami, as in the Gulf of Cadiz region in 1755 when tsunami run-up heights reached 10 m. Great earthquakes (M 8–9) and tsunamis occur in the Gulf of Cadiz with a repeat time of 1.5–2 k.y., according to the sedimentary record. An unusually thick turbidite dated as ca. 12 ka may coincide with the destructive event in Plato's account. The detailed morphology of Spartel paleoisland, as determined from recently acquired high-resolution bathymetric data, is reported here. The viability of human habitation on this paleoisland ca. 11.6 ka is discussed on the basis of a new bathymetric map.