The modern legend of the Loch Ness Monster was born in 1933 when Mrs Aldie Mackay, manageress of the Drumnadrochit Hotel, spoke of seeing a “whale-like fish” in the loch from the passenger seat of a car. 

Despite 90 years of expeditions, scientific tests, sonar surveys, grainy photographs – some less convincing than others - and the deployment of a yellow submarine, Nessie remains as elusive and enigmatic as ever.

Now filmmakers claim that DNA tests have shown that the Loch Ness Monster is an algae-based creature.

Investigators collected water samples from the famous loch's Borlum Bay during the largest search for Nessie in over 50 years.

Matty Wiles, 49 and Aga Balinska, 42 were volunteering as part of the search, which took place over the last weekend of August this year.

READ MORE: Documentary film on Loch Ness Monster-hunting boom in 1970s hits UK cinemas

They went for an early morning swim at 6.30am and saw two humps and a third appendage, possibly a head, in the water.

They took photos and videos and shared their findings with Loch Ness Exploration, a group set up to research the mysteries of loch and coordinated the search.

Documentary producers working on new TV series Weird Britain, by Dragonfly Films, were there to chronicle the hunt for Nessie as the season finale of their series.

They decided to collect water samples to send for eDNA - environmental DNA - analysis - a new method of amplifying traces of DNA left behind by an animal in its habitat. 

The samples were sent to a private laboratory in Colorado, USA, which was founded in 2013 with the aim of helping other scientists answer ecological questions by sequencing environmental DNA.

The Herald: Experts claim Nessie may be algae-basedExperts claim Nessie may be algae-based (Image: Dragonfly Films)

The tests detected two types of algae, with experts claiming it suggests Nessie may be algae-based.

American TV presenter and cryptozoologist Ken Gerhard said: ''The tests only detected algae, which of course is exciting news if we consider the possibility that Nessie is a giant algae blob monster.”

The site where the water sample was collected was also made famous in 1934 when a housemaid at Kilchumein Lodge sighted the legendary beast.

Margaret Munro said she watched it through binoculars as it rolled about on the shingled beach of Borlum Bay. She described it as being grey and having a long neck, small head, large body, flippers and humps.

The show’s producer, Tim Whittard, said: “The ability to now make use of new eDNA analysis techniques presents an exciting step forward for wildlife researchers, and may help us to find answers to some of the most fascinating and puzzling mysteries of the natural world.”

READ MORE: Nessie at 90: How Scotland's monster captured imaginations around the world

The new TV show, which is set to be released in early 2024, follows in the footsteps of a  feature-length documentary which hit UK cinemas on November 10.

Loch Ness: They Created A Monster uses rare archive footage to offer a new take on offers a new take on the Loch Ness Monster-hunting boom of the 1970s, which saw everyone from WW2 veterans to Japanese pop impresarios descend on the loch in the hope of catching the ultimate prize.

The documentary, directed by three-time Scottish BAFTA winner John MacLaverty (Scotland 78: A Love Story), turns the lens on the great Nessie hunters of the 1970s - and how their quest descended into chaos, monster egos and violence. 

The 1970s saw a well organised ‘official’ expedition by the Loch Ness Investigation Bureau, which strategically placed vans and cameras around the loch and watched it non-stop, year after year, coming up with very little evidence. 

Meanwhile, there was also the 'International Loch Ness Monster Search Party' led by the eccentric Japanese pop promoter Yoshio Kou, who happily declared that he wanted to capture Nessie and take her around the world.