B.C. boaters warned to avoid floating island that has mystified experts

Geologist John Joseph Clague said when he first heard that a floating island, bigger than a football field, had been spotted on a lake in British Columbia’s northern Interior, he dismissed it as an “AI stunt.”

But Clague — a professor of earth sciences at Simon Fraser University and an emeritus scientist of the Geological Survey of Canada — is now convinced that the island is very real, but is mystified by its origins.

Boaters have been being warned to stay off the island that reappeared on Monday on Williston Lake, the reservoir for the W.A.C. Bennett Dam, after BC Hydro confirmed its existence in mid-August but then lost track of it..

BC Hydro spokesperson Bob Gammer said it had travelled about 30 kilometres, adding to the mystery surrounding the island that he theorized had been formed when it was lifted free by rising water levels in the reservoir.

Clague, who has previously worked around the Williston Lake area, was not convinced by that explanation. He said he had seen evidence of erosion along the lake, but “nowhere near that in scale.”

“There is erosion occurring, and trees do collapse into the lake, but they don’t kind of form this very large mat of forested material,” said Clague. “This is unusual. I’ve never heard of such a thing before.”

He said it also remained a mystery why the island had not broken apart after travelling so far.

“I think a lot of people view it as something that’s very thick, but it can’t be thick if it’s moving around the lake at speeds,” said Clague, “So, you know, it’s a curiosity.”

Rocky Avery shared images of the island that drew worldwide attention after it was spotted by a friend at the lake north of Avery’s hometown of Mackenzie last month.

He said the water under the island at the time was about 60 metres deep.

“When I saw the video, it was just kind of in awe because you can see from his boat — he was making the ripples, and you could see along the island it was all just going up and down, and it was actually real,” said Avery. “It was crazy.”

Avery notified BC Hydro and members of the Tsay Keh Dene First Nation of the discovery.

Gammer said he too initially thought the reports of a floating island covered in trees and foliage were a hoax when BC Hydro received them on Aug. 13.

“I checked internally and nobody that I have with contacts in the company had heard of this either. So, at the time, we basically thought it was maybe a hoax, and we didn’t give it much more attention,” said Gammer, manager of northern community relations with BC Hydro.

But a few days later, engineers with the Crown utility spotted it on satellite imagery in Finley Bay, near the centre of the lake.

“This is a rare occurrence, and certainly the first that we’ve heard of for Williston reservoir,” said Gammer.

He said they tried to track the island but it seemed to vanish, before it was spotted again on Monday against the shoreline where the Ospika River flows into the lake.

“It’s moved about 30 kilometres northwest on the reservoir into a more remote location,” said Gammer. “It looks like the island appears to be intact.”

Gammer said he also received a photo from a boater, providing double confirmation of the island’s reappearance. Based on satellite imagery, the island is about 140 metres long and about 70 metres wide, he added.

He said boaters should resist the urge to visit the island, theorizing that it was based on an unstable mass of logs and decaying debris that may have broken free from the shore when the lake recently filled for the first time since 2012.

Gammer said the island’s origin was not certain but it was normal for trees that fall into the reservoir to clump together in sheltered bays.

“You can imagine, like a tree falling down in the forest, and the trunk is laying flat, and over a long period of time, it starts to break down, and other plants, moss, and even trees start growing on top,” said Gammer.

The rising waters of the reservoir then could have lifted the mass free, calling it the “best theory” of how the island came to be.

Gammer said waves in the reservoir can become violent during a windstorm and he feared they could tear apart the mass of logs and woody debris.

“It’s just naturally unstable, and so it’s unsafe to climb onto the island or land a boat on it. It would be dangerous to do that,” he said.

BC Hydro would continue to monitor the island to see if it started moving again, Gammer said.

“I mean, there will be people who will probably want to study it and get close to it. So, there may be more information to come about the island as the weeks go by,” said Gammer.

Avery cheered news the island hadn’t sunk, after being told by members of the Tsay Keh Dene First Nation that they too had spotted it again.

“We’re just waiting for the water to calm down so we can take a jet boat and take a better look at it,” said Avery, adding a former chief from the nation would join the trip to inspect the island.

Avery said he had lived in the area for more than 48 years and never heard of anything like the island before.

He said he wanted the island to be named Rocky Island — “even though it’s not that rocky.”

This report by The Canadian Press was first published Sept. 1, 2026.

Nono Shen, The Canadian Press