Situated on the coast of Suffolk, England a few miles from the town of Walberswick, in the 13th century Dunwich was England's 5th largest port. However, soon after the town began to slowly sink into the sea, mainly as a result of erosion. Now almost all the town is underwater, except for a ruined abbey (left over from the dissolution of the Monasteries) and a rather nice fish and chip shop (although that might have been washed away since as well.)
There is a myth that the bell on the Church, which is now probably over 100 metres out to sea, can still sometimes be heard ringing beneath the sea.