SOUTHAMPTON, ENGLAND—David Sear of the University of Southampton has created the most accurate map to date of the submerged medieval port town of Dunwich, on England’s eastern coast. Sear recorded the town’s streets, boundaries, and major buildings in the murky, muddy water, by combining high-resolution acoustic imaging with old charts and navigation guides. Beginning in 1286, storms eroded the coastline and silted up the Dunwich River and eventually the town’s harbor. By the fifteenth century, Dunwich was no longer viable. “Everyone was surprised, though, by how much of the eroded town still survives under the sea and is identifiable,” commented Peter Murphy of English Heritage.