The above map shows the parish boundary of Blythburgh (red diamonds) in relation to the 5-25m contours and the surrounding villages. It's northern boundary is the River Blyth. The western and northern boundaries for the most part follow streams that divide it from Dunwich, Darsham, Thorington and Wenaston. The 25m contour roughly marks the boundary between the water-borne sands and gravels and the glacial clays. To the northeast Blythburgh is separated from Walberswick by a shared boundary, marked by ancient trees, that cuts across the watershed between the Blyth and Dunwich rivers. This is an indication that Walberswick was once part of Blythburgh, which in the Domesday survey is listed as one manor. There is no mention of Walberswick in Domesday, but a reference to the rendering of thousands of herrings to the Crown implies that there was a busy sea fishery belonging to Blythburgh at the mouth of the river. Throughout the Middle Ages, the lord of the manor of Blythburgh was also lord of Walberswick but there is no evidence as to when Walberswick was split off from Blythburgh. Hinton and Westwood remained hamlets within the ecclesiastical parish of Blythburgh. The village of Blythburgh (the civic parish) was defined as the community situated close to the parish church. In modern times, Bulcamp was included as another hamlet of Blythburgh.