Neil Gemmell has travelled from the University of Otago in New Zealand to collect water samples in the Scottish lake, in the hope of finding out more about the creatures that inhabit its depths.

"Over 1,000 people claim that they have seen a monster. Maybe there is something extraordinary out there," he told AFP, as he dropped a five-litre probe into the loch.

Gemmell said he would be keeping an eye out for "monster DNA" but the project was more aimed at testing environmental DNA techniques to understand the natural world.

Local resident Adrian Shine said Gemmell's findings could contribute to his own long running research programme -- The Loch Ness Project.

The venture was itself inspired by the efforts of earlier international explorers like American Dan Scott Taylor who patrolled the loch in his Beatles-inspired Yellow Submarine in the late 1960s.

"I'm sure that some species will be found which have probably not been described. They're more likely than anything else to be bacteria," Shine told AFP.

"If you did find something else -- and I do emphasise the if -- then you would actually get quite a good handle on what sort of creature, what class of animal, it is."

'Record number of sightings'

Theories abound about the true nature of the Loch Ness Monster, from a malevolent, shape-shifting "water horse", to an aquatic survivor of the dinosaur age, right down to logs, fish, wading birds or simply waves which have been blown out of all proportion.

"Anything that you see on the loch that you don't understand can be your Loch Ness Monster on that day," Shine said.

The earliest chronicles of a creature in Loch Ness are attributed to Saint Columba, who brought Christianity to Scotland in the sixth century.

The last reported sighting was on March 26 this year by a US couple standing on the ramparts of the majestic ruin of Urquhart Castle.

"They described a large shadow moving under the water which they estimated to be around 30 feet in length," said Dave Bell, skipper of the Nessie Hunter tourist boat.

"Last year we had a record number of sightings: 11 in total."

Bell has never seen anything himself in his many years on the loch, but that does not shake his belief that there is something down there.

"I find it hard to believe that over 1,000 people can be wrong," he said.

"Too many rational, level-headed people have said they have seen what they believe to be a creature in the loch."

Tourism boom

The Highlands are experiencing a boom in tourism -- and not all of it is related to mythical monsters.

Inverness is the gateway to the North Coast 500, a new 500-mile (800-kilometre) trail dubbed "Scotland's Route 66" which attracted 26 percent more tourists to the area last year, according to the Highlands and Islands Enterprise agency.

"There's a lot more people around," said Joanna Stebbings, operations manager at Loch Ness Lifeboat Station, which carried out a record 33 rescues last year.

"All the hire companies, whether they are kayaks or cruisers or even yachts are fully booked."

Andrea Ferguson, 56, a school teacher from Saint Louis, Missouri, took a trip on Nessie Hunter to try to catch sight of the monster which has fascinated her since childhood.

"So many sightings have been made that there may be a little truth to the Loch Ness Monster," she told AFP.

"The loch is huge. It's even bigger than I thought it was.

"It's dark water, very mysterious, there's lots of fog and mist, and large mountains draped in clouds so it has an aura of majesty and mystery about it. It's beautiful!"