Irish missionary St Columba is first said to have encountered a beast in the River Ness in 565AD.
Among the most famous claimed sightings is a photograph taken in 1934 by Colonel Robert Kenneth Wilson.
The image was later exposed as a hoax by one of the participants, Chris Spurling, who, on his deathbed, revealed that the pictures were staged.
Other sightings include James Gray’s picture from 2001 when he was out fishing on the Loch, while namesake Hugh Gray’s blurred photo of what appears to be a large sea creature was published in the Daily Express in 1933.
Many have tried to explain the sightings, including ‘Nessie expert’ Steve Feltham, who has spent 24 years watching the Loch. In 2015 he said he thought it was actually a giant Wels Catfish, native to waters near the Baltic and Caspian seas in Europe.
In April a scientist from New Zealand revealed plans to DNA test the waters of Loch Ness in another bid to determine if Nessie exists.
Professor Neil Gemmell from the University of Otago will look for traces of unusual DNA by gathering water samples from before analysing them using police forensic techniques.
According to Google, there are around 200,000 searches each month for the Loch Ness Monster, and around 120,000 for information and accommodation close to Loch Ness. The monster mystery is said to be worth £30million to the region.