Divers working on a wind farm project have discovered the wreck of a German U-boat sunk more than 100 years ago.
SM U-31 - which disappeared after leaving Germany on 13 January 1915 - was found 56 miles off the coast of East Anglia.
Video footage shows the 57.6m-long vessel lying 30m down in the North Sea, with damage to its bow and stern.
The wreck was discovered by Scottish Power Renewables and its partner Vattenfall in 2012, but has only now been officially identified.
Mark Dunkley, marine archaeologist at Historic England, said: "SM U-31 was commissioned into the Imperial German Navy in September 1914.
"On January 13 1915, the U-31 slipped its mooring and sailed northwest from Wilhelmshaven for a routine patrol and disappeared.
"It is thought that U-31 had struck a mine off England's east coast and sank with the loss of its entire complement of four officers, 31 men.
"The discovery and identification of SM U-31 by ScottishPower Renewables and Vattenfall, lying some 91km east of Caister-on-Sea, Norfolk, is a significant achievement.
"After being on the seabed for over a century, the submarine appears to be in a remarkable condition with the conning tower present and the bows partially buried.
"Relatives and descendants of those lost in the U-31 may now take some comfort in knowing the final resting place of the crew and the discovery serves as a poignant reminder of all those lost at sea, on land and in the air during the First World War."
Andy Paine, Vattenfall project director of East Anglia Offshore Wind Farm, said the receiver of the wreck and other authorities have been informed.