Archaeologists believe that photographs taken along the Suffolk coast may prove that the ancient city of Dunwich may have been connected with shipbuilding.
Recent exceptionally low tides have revealed timbers and banks that experts say may be connected with shipbuilding at Dunwich nearly 500 years ago.
Photographs taken by members of the Suffolk Underwater Studies group show piles driven into the sea bed.
Director Mr Stuart Bacon said "They might well be a shipyard slipway."
Jane Chick, from Halesworth, one of the beach observers, happened to go on that stretch of beach 10 days ago at low tide and took photographs of what she thought were sea defences.
"I interpreted them as something entirely different to that and highly exciting," Mr Bacon said.
"They might well be slipways used for shipbuilding or might be an anchorage point or quay or a support for a landing area for boats.
"I am confident that they are part of a complex connected with the declining port of Dunwich and whilst I have seen piles more than 30 years ago what these photographs show is something entirely new," he said.