At least according to the British Broadcasting Corp., which says a team which trawled the loch for any signs of the famous monster came up with nothing more than a buoy moored several yards below the surface.
The team used 600 separate sonar beams and satellite navigation technology to trawl the loch, but found no trace of any monster, the BBC said in a television program broadcast Sunday.
Previous reported sightings of a large beast in the gray waters of the lake led to speculation that the loch may contain a plesiosaur, a marine reptile which died out with the dinosaurs.
The BBC researchers said they looked at the habits of modern marine reptiles, such as crocodiles and leatherback turtles, to try to work out how a plesiosaur might have behaved.
They hoped the air in Nessie's lungs would reflect a distorted signal back to their sonar sensors.
"We went from shoreline to shoreline, top to bottom on this one, we have covered everything in this loch and we saw no signs of any large living animal in the loch," said Ian Florence, one of the specialists who carried out the survey for the BBC.
His colleague Hugh MacKay added: "We got some good clear data of the loch, steep sided, flat bottomed — nothing unusual I'm afraid. There was an anticipation that we would come up with a large sonar anomaly that could have been a monster, but it wasn't to be."
The BBC team said the only explanation for the persistence of the monster myth — and regular "sightings" — is that people see what they want to see.
To test this, the researchers hid a fence post beneath the surface of the loch and raised it in view of a bus full of tourists.
Interviewed afterward, most said they had observed a square object but when asked to sketch what they had seen, several drew monster-shaped heads, the BBC said.
There have been reports of sightings of a "monster" in the loch since the time of St. Columba in the 6th century.
Many who have reported sightings have described a beast similar to a plesiosaur, but experts say it is 65 million years since the last fossil record of plesiosaurs. Loch Ness is only 10,000 years old, so anything living there must be much younger.
BBC TV plans to broadcast a documentary on the investigation, "Searching For The Loch Ness Monster."