Art Folden's Ogopogo film, Okanagan Lake (1968)

Okanagan Lake runs long and narrow through the interior of British Columbia. For generations, people have spoken of something living in it. The Syilx/Secwepemc name is Nx̌ax̌aitkʷ, or N'ha-a-itk, and Westbank First Nation voices describe it as a sacred protector spirit, not a demon. Most people today call it Ogopogo. In 1968, it was about to be caught on film.

Summer, 1968. Arthur "Art" Folden, of Chase, B.C., was driving along Highway 97 beside the lake with his wife. Folden was a home movie buff. Out on the calm water, he noticed something large and lifelike. He pulled off the road and started filming.

The film begins with a disturbance in the water. A dark object moves to the right of the frame and picks up speed, cutting a noticeable wake. It dives. It reappears, as if moving out from shallow water into deeper water. One account says it broke the surface of Okanagan Lake much as a submarine would.

Folden judged it to be about 100 m offshore. Another account puts it at 300 yards. Forty feet long in one telling. Sixty feet long and 3 feet wide in another. About 70 feet in a third, big enough to dwarf the pine trees in the foreground of the film.

By several accounts, Folden did nothing with the footage until his brother persuaded him to make it public. Released around 1970, it was later bought by Kelowna journalist Arlene Gaal, who had it professionally analysed. By her account, it was not a hoax, and the object could not be conclusively explained. A computer analysis concluded it was a solid, three-dimensional object. The footage appeared on Arthur C. Clarke's Mysterious World, and the Folden film is described in the Ogopogo segment of Unsolved Mysteries.

In 2005, the National Geographic Channel series Is It Real? returned to the lake. The team was Benjamin Radford, Joe Nickell and John Kirk of the British Columbia Scientific Cryptozoology Club. They used surveyor boats to find the actual distance of the object from shore. The answer changed the story. The object had been much closer to shore than originally thought. Its size shrank. So did its speed.

Radford later wrote: "Through scientific experiments, we concluded that the object Folden filmed was in fact a real animal (and not a wave or floating log), but its size had been greatly overestimated. It was probably a water fowl or beaver that was too far away to be properly identified." Other accounts of the finding add otter to the list.

No one accuses Folden of a hoax. Believers and skeptics agree that he filmed something real on the water. The argument is about what it was, and how big. The British Columbia Scientific Cryptozoology Club still presents the film as evidence that Ogopogo is not merely an optical illusion caused by wind, waves or known animals. Skeptics point to the survey, and to the wake of a beaver.

The Folden film is often paired with Larry Thal's 1980 footage as one of the two best films of the creature, a claim made by the visitor centre in nearby Peachland. Radford and Joe Nickell examined both in their 2006 book Lake Monster Mysteries. More than half a century on, a minute of home movie from a roadside pull-off is still at the centre of the Ogopogo debate.