Two submarine wrecks, believed to be uncharted WWI German U-boats, have been discovered by chance off Orkney.
A team working on a Maritime and Coastguard Agency (MCA) tug made the find during a routine sonar survey.
The submarines - reported missing in the area in 1918 - were discovered about 70 miles off Sanday Sound.
One was under the control of Commander Kurt Beitzen, who had previously mined and sunk HMS Hampshire carrying Lord Kitchener in 1916.
Plans of the two U-boats have been examined by experts, who have identified the wrecks as U-102 and U-92, which may have been sunk by a series of mines.
Rob Spillard, hydrography manager for the MCA, said: "One of the subs it seems was commanded by quite a famous commander - the man who sank the ship that Lord Kitchener was on - so this is his watery grave so to speak."
On 23 May, 1916, U-75 laid mines under the control of Commander Beitzen after travelling around the west coast of Orkney undetected.
Less than a month later the head of the war ministry, Lord Kitchener, was lost at sea together with many of the crew of the cruiser HMS Hampshire after striking mines.
The discoveries were made by chance by the MCA team
He has been well remembered for his famous recruitment posters, bearing his heavily moustached face and pointing hand, over the legend "Your country needs you".
Beitzen later transferred to U-102, which was on its way home to Germany in autumn 1918 when it was lost with all 42 hands.
The MCA was one part of the team involved in the recent ScapaMap survey, which successfully mapped the locations of the remains of the German fleet scuttled at Scapa Flow in 1919.
The discovery of these U-boats was not part of the Scapa Flow project but part of the MCA's ongoing process of undertaking hydrographic surveys in UK waters.
Mr Spillard said: "The tug's main role is to intervene when large vessels require towing away from the coast in order to protect shipping, lives and the environment.
"The MCA have fitted state-of-the-art sonar equipment to the tug. Whilst the tug is on standby for any incident that may occur, it is put to good use collecting hydrographic survey data."