Monster mania on Nessie's anniversary

Some believe that those who claim to have seen the Loch Ness Monster are unfairly mocked; others that they are not taking enough water with their whisky. But today, Nessie enthusiasts will commemorate 80 years since the first modern "sighting" of the creature at the centre of one of the world's greatest and most enduring mysteries.

The possibility of a fantastical beast lurking beneath the waters of the Scottish loch has inspired newspaper headlines, Hollywood films and a tsunami of tourist trinkets. And this morning, Nessie buffs will head for Loch Ness to raise a glass to Mrs Aldie Mackay, the woman whose sighting sparked the phenomenon – as well as a highly lucrative tourist boom.

On 14 April 1933, Mrs Mackay, who is now dead, was travelling with her husband by car from Inverness to her home in Drumnadrochit when she spotted a "whale-like fish" in the loch. Upon seeing what she thought was a hump in the water, she reportedly exclaimed: "Stop! The Beast!" A large wave spread across the water towards the pier on the opposite shore; about halfway across, two black humps emerged, moving in line, the rear one larger than the front. By the time Mr Mackay had stopped the car, "The Beast" had gone, and he failed to catch a look.

The couple kept the incident a secret until Mr Mackay let the story slip to the water bailiff, Alex Campbell, who was also a part-time journalist.

He recorded the sighting in the Inverness Courier under the headline: "Strange Spectacle in Loch Ness". The article stated: "The creature disported itself, rolling and plunging for fully a minute, its body resembling that of a whale, and the water cascading and churning like a simmering cauldron. Soon, however, it disappeared in a boiling mass of foam. Both onlookers confessed that there was something uncanny about the whole thing, for they realised that here was no ordinary denizen of the depths."

Adrian Shine, a naturalist and, for 40 years, a Loch Ness Monster expert who tracked down Mrs Mackay in the late 1980s, said: "Her exclamation of 'Stop! The Beast!' is highly revealing as it suggests there was a form of tradition. However, she was highly reticent and didn't want to tell anybody because she thought it would be self-advertising. I also pressed her on whether there was a tradition. She said there was, and that 'people should take more water with it!'"

Since that first glimpse in 1933, there have been many more claimed sightings of Nessie, but also many sources of deception. Among them are animals including otters, deer, seals and ducks, as well as other red herrings such as boats and logs.

There have also been many hoaxes. Marmaduke Wetherall's spoof footprints in December 1933 were made with a stuffed hippopotamus foot. Wetherall and his son also appear to have been responsible for the notorious "Surgeon's Photograph", now believed to show a toy submarine modified by the addition of a head and neck.

Scientists suggest boats producing powerful waves may have given rise to some sightings too. Nevertheless, the legend of Nessie lives on.