Hjörtur Kjerúlf's Lagarfljót Worm video

Lagarfljót is a long lake near Egilsstaðir in East Iceland, 25 km long and 112 m deep. For centuries it has kept a monster. The Icelandic annals for 1345 recorded a "wonderful thing" with humps above the water, and Ortelius's 1585 map of Iceland noted a serpent menacing the inhabitants. Modern sightings followed, including one in 1963 by Sigurður Blöndal, head of the forest service. In 1997 a local council offered 500,000 krónur for proof, but nobody claimed it.

February 2, 2012. That morning, Hjörtur Eiríksson Kjerúlf, a 67-year-old farmer, was having his coffee at his farmhouse at Hrafnkelsstaðir in Fljótsdalur. From the kitchen window he saw something moving in the glacial river Jökulsá í Fljótsdal, where it flows into the inner end of Lagarfljót. The object was long and very slender. It moved like a snake, appeared to him to have the head of a crocodile, and seemed to swim against the current.

He finished his coffee. It was still there. So he picked up his camera and filmed it. The clip runs about 30 seconds. Snow, ice floes and fast, muddy meltwater. A dark shape undulates in the middle of it all and seems to push upstream.

The footage was first published on the website of RÚV, Iceland's national broadcaster, and ABC News, NBC News and the Daily Mail took it worldwide. Within days it had passed a million views, and Austurfrétt later put the total at 8 million. Kjerúlf rejected any suggestion of trickery. "That is ridiculous. This is no joke."

Asked whether he believed his own footage, he answered: "Þórbergur Þórðarson said it characterized the inhabitants of Hérað that they never believed what they saw. I'm not like that." In May 2012 a crew from Fact or Faked: Paranormal Files arrived, led by host Ben Hansen. About 20 people camped at Hrafnkelsstaðir.

The district council of Fljótsdalshérað set up a Truth Committee on the Existence of the Lagarfljót Worm. Its 13 unpaid volunteers included town councillors, a biologist, an ethnologist, a pastor, a former MP and the chairman of the Association of Amateur Monster Researchers. Stefán Bogi Sveinsson chaired it. In May 2014 it asked for more time, noting that "numerous comparable videos have appeared on YouTube".

The verdict came in August 2014 at the Ormsteiti Worm Festival, where seven members said the video shows the Worm, four said no and two abstained. The committee found "no reason to doubt that there was some kind of creature or being in the water." Kjerúlf received the prize. "Ormurinn er til!" he said. The Worm exists.

In 2012, Finland-based researcher Miisa McKeown studied the clip frame by frame against fixed points. "The 'monster' is actually stuck in one place on the river," she said. "The snaky thing looks as if it's swimming upstream because water is streaming past it." Her likely culprit was a net or a long piece of cloth snagged under the surface, given its segmented look by chunks of ice.

Loren Coleman of the International Cryptozoology Museum saw "something that looks like a constructed snake-like object, with rigid sections, being propelled through the water." He raised the possibility of deliberate fakery. Others criticised the committee's vote as an attempt to attract cryptotourism visitors.

The coverage reached for one comparison above all, Loch Ness. Stefán Bogi Sveinsson admitted the committee never saw the creature itself: "We didn't see the Worm, but we tried really hard to look for it." Yet in the valley the legend endures. "People around here have seen it," he said. "Quite a lot of people."