Experts to examine River Foyle, Derry, wreck
The environment minister is to call in experts to identify a wreck found in the River Foyle, which could be a World War II submarine.
Alex Attwood has banned diving at the site of the discovery near the Foyle Bridge.
He said it was important that the wreck was not disturbed until it was positively identified
"The wreck is in quite low water, it is quite accessible," Mr Attwood said.
"Given that we don't know how it came to be there, we need to be extra vigilant, given the risk of munitions on board and the risk that this might be a war grave."
Foyle Search and Rescue's Paddy Wilson said: "It's great for the city - it's a great mystery in itself. This city could have its own Titanic.
"I think that's the mystery of it - we just don't know exactly what it is.
"I suppose we're all hoping that it's going to be a German U-boat that has come up to spy on the Americans and the British and some way has got into trouble and couldn't surface."
However, BBC Northern Ireland Environment Correspondent Mike McKimm said that was unlikely.
"Sources say it is unlikely to be a full-sized submarine.
"A German U-boat, for example, would sit almost 10m high and would have been visible, even at high tide in the Foyle, which has an average depth of just over 5m."
He said there was speculation that the vessel could be a mini or midget submarine from the war.
"These would be just a couple of metres high. In 1944 the German navy operated a very successful two-man mini-sub, the Seehund.
"It saw operations in the English Channel and the North Sea.
"Piggy-backing on a large U-boat, the Seehund had the capability of reaching the Foyle where there was intense naval and merchant navy activity," he said.
"The river and its estuary also offered the nearby shelter of a neutral country if it all went wrong.
"Another World War II German mini-submarine, the one-man Biber, specialised in river and estuary attacks but had a very limited range."
At the end of the war, German submarines surrendered in the Foyle from where they were taken out to sea and destroyed or sunk.
The vessel could also be a British two-man mini submarine - known as an X craft, a small boat or even a private yacht - one is known to have sunk in the area many years ago.
"It's all speculation until divers can reach the wreck," Mike McKimm said.
"Diving is not expected to start for a week or so. Underwater visibility in the Foyle is very poor at the best of times making identification difficult."