The submarine, detected some 90 kilometers (56 miles) off the coast of the English county of Norfolk, was identified as the German U-boat U-31.

Workers from ScottishPower Renewables discovered the wreck while doing research for a North Sea wind farm development in 2012.

Officials from the company contacted the Royal Netherlands Navy, which was looking for a Dutch military submarine that went missing in June 1940. A team of Dutch divers investigated the 57-meter-long wreck (190 feet) and filmed it as it lay preserved on the sea bed.

It took three years to identify the submarine, given the murky water conditions around it.

'Positive closure for descendants'

Studies revealed that it was the U-31, which set off on patrol on January 13, 1915, but never returned. All 35 men on board are believed to have perished.

"Unraveling the whole story behind the submarine has been fascinating," said Charlie Jordan, a project director with ScottishPower Renewables. "It's heartening to know that the discovery will provide closure to relatives and descendants of the submariners lost who may have always wondered what had happened to their loved ones."

Mark Dunkley, a marine archaeologist with the Historic England preservation organization, said the vessel was in "remarkable condition."

"The discovery serves as a poignant reminder of all those lost at sea, on land and in the air during the First World War," he said.

During World War I, U-boats were the sole weapon Germany had when attempting to impose a naval blockade on Britain, given the island nation's superior power at sea.

rc/sms (AFP, dpa)