- Developers discovered the vessel in September of 2012
- Taken four years to ID because of murky conditions
- Developers were surveying more than 3,700 square miles, when they discovered wreck
(CNN)A century-old wartime vessel has been identified off the coast of England.
Wind farm developers were scanning the seabed off the coast of Norfolk and Suffolk when their sonar detected an unusually large object 55 miles from shore.
From the outlines on the sonar scans, the object appeared to be a submarine, Paul Ferguson, a spokesperson for the energy company ScottishPowers Renewables, told CNN.
Developers were surveying a part of the Southern North Sea that spanned more than 3,700 square miles, four-times the size of Greater London, their scans revealed 60 wrecks and indicated a wide variety of vessels. But this wreck was different, Teri Nicklin of ScottishPowers Renewables said.
"It was a really special day. We were looking for wrecks, but what we found was a huge wreck that didn't appear in any of the charts," Nicklin said.
The submarine was an uncharted mystery.
Developers discovered the vessel in September of 2012. The energy company notified the authorities and reached out to the Royal Netherlands Navy, which was searching for a Dutch military submarine that went missing in action in June 1940, after the crew was patrolling the waters between Denmark and Norway.
It's taken about four years to identify the submarine's origin because murky water conditions in the East Anglia region made it impossible to see the vessel. In recent months, Dutch Navy divers were able to uncover the submarine's identity. It is named U-31, a German U-boat from World World I.
The U-boat was 189 feet long, 13 feet wide and 15 feet high. The vessel appeared to have damage on the bow and stern, and it may be possible the vessel was originally longer, according to a press release by ScottishPower Renewables. Otherwise, the submarine looked relatively intact, Nicklin said.
It is believed that U-31 was destroyed by a mine off England's coast and sank with its entire crew of four officers, 31 men, Mark Dunkley, marine archaeologist at Historic England said.
The English waters will be the U-boat's final resting place, but authorities will try to contact German families who may have had relatives on the vessel, Nicklin said.
One hundred years ago, there were people in Germany whose family and friends were lost on the submarine, Nicklin said. "It's just lovely to think that something we're doing now for future generations has been able to end the story for a lot of people in Germany."
Developers plan to start construction of the wind farm in 2017, but will stay clear of wartime relics that are resting on the ocean's floor.