Experts believe that a wreck discovered by subsea engineers could be the remains of SM UB-85, which went down in folklore after disappearing beneath the waves in 1918.
Official reports from the time tell how UB-85 was caught on the surface on April 30, 1918, by British patrol boat, the HMS Coreopsis.
The submarine”s crew surrendered without resistance to the surprise of the British.
However, legend has it that, when quizzed about why it was cruising on the surface, the U-boat”s commander Captain Gunther Krech recounted how the sub was recharging its batteries at night when a “strange beast” rose from the sea.
He is said to have described a “beast” with “large eyes, set in a horny sort of skull” and a “small head, but with teeth that could be seen glistening in the moonlight”.
The monster was so large that it is claimed it forced the U-boat to list greatly to starboard.
Krech is believed to have said: “Every man on watch began firing a sidearm at the beast.”
He said that, during the struggle, the forward deck plating was damaged, preventing the vessel from submerging.
“That is why you were able to catch us on the surface,” the Captain is said to have told the British.
The mystery has spanned almost a century but it may now be solved – after marine engineers laying one of the world”s largest subsea power cables stumbled upon the remains of what is thought to be the vessel.
It was discovered by a team working on the Western Link project, a joint venture between ScottishPower and National Grid which will take renewable power from Scotland to homes and businesses in England and Wales, believe they have now found the wreck.
Sonar images show the 100-year-old vessel largely intact and attempts to identify the wreck have led experts to conclude that it may be that of UB-85.
Innes McCartney is an historian and nautical archaeologist who is helping the team to identify the wreck.
He said: “Unless a diver can find a shipyard stamp, we cannot say definitively but yes, we”re certainly closer to solving the so-called mystery of UB-85 and the reason behind it”s sinking – whether common mechanical failure or something that is less easily explained.”
Although many believe the wreckage will provide a rational explanation for the sinking, Gary Campbell, keeper of the Official Sightings Register of the Loch Ness Monster, insisted it was “entirely feasible” a “large sea creature” was responsible.
He added: “History has shown that there have been consistent reports of large “monsters” not just in lakes and lochs like Loch Ness but out in open waters as well.”