An amateur photographer believes he may have photographed Nessie, the world's most famous cryptid.
The image was taken by David Elder at Fort Augustus, at the south-west end of the 23-mile-long body of water in northern Scotland.
It shows a long bow wave apparently caused by some sort of disturbance on the surface of the loch.
Mystery: This bizarre picture of an unexplained phenomenon was taken from the shore of Loch Ness
The 50-year-old photography enthusiast insists the only thing that could have caused it is 'a solid black object under the water'.
Mr Elder, from East Kilbride in Lanarkshire, was able to take still photos as well as filming a video of the mysterious scene.
'We were at the pier head at Fort Augustus and I was taking a picture of a swan at the time,' he said.
'Out of the corner of my right eye I caught site of a black area of water about 15ft long which developed into a kind of bow wave.
'I'm convinced this was caused by a solid black object under the water. The water was very still at the time and there were no ripples coming off the wave and no other activity on the water.
'Water was definitely going over something solid and making the wave. It looks like the sort of wave perhaps created by a windsurfing board but there was nobody on the loch at the time, no boats, nothing.
'The disturbance in the water began moving up the Loch sideways. It is something I just can't explain.'
The extraordinary picture will doubtless fuel the imaginations of anyone who believes the story that there is a sea creature living in the lake, which is Britain's largest due to its 230m depth.
However, sceptics will ascribe the wave to a freak gust of wind or other natural phenomenon.
Iconic: This is the 'surgeon's photograph' taken in 1934 which purports to show the Loch Ness Monster
The story of the Loch Ness Monster goes back as far as the medieval period, but it first came to widespread public attention in 1933.
That year a couple named the Spicers claimed to have seen a creature with a large body and long neck jumped in to the loch, causing a national sensation.
The next year, the iconic 'surgeon's photograph' was published, purporting to show the creature swimming in Loch Ness with its head out of the water.
Although that image has been debunked as a hoax, the search for Nessie has continued, with true believers undeterred by the failure of repeated attempts by scientists to find the creature.
The 13th century Urquhart Castle on the banks of Loch Ness was granted to the Clan Grant in 1509. Urquhart was partially destroyed in 1692 to prevent its use by Jacobite forces, and subsequently decayed. In 2008 Loch Ness was voted by the British public as Britain's favourite domestic attractions and is considered to be one of the Seven Wonders of Britain
Loch Ness is Britain's fourth largest lake and the second-deepest. It contains more fresh water than all the lakes in England and Wales combined, and is the largest body of water on the Great Glen Fault, which runs from Inverness in the north to Fort William in the south. It could hold the entire world's human population ten times over.