The mysterious object filmed by the US Government’s Bureau of Land Management (BLM) has yet to be identified but the agency confirmed the footage is genuine.
The alleged ‘sea creature’ was caught gracing the surface of the Chena River in Alaska.
In the video, the object wades through the icy river – and even the BLM admits it is “not sure” what the strange phenomenon is.
In the video, the object swirls back and forth in the current for several minutes.
Footage of the sighting has quickly gone viral, attracting tens of thousands of views.
Craig McCaa, the Government agency worker who spotted the eerie object, has been shocked by what he saw.
He said the worldwide response show “how strongly the mysteries of the natural world capture our imagination”.
He added: “I initially thought, and several people thought, it could be some rope that snagged on the bottom of the river with chunks of ice.
“Other people have mentioned everything from a sea monster to a giant sturgeon.”
On its own Facebook page, BLM wrote: “Our employees did not investigate. It’s kind of far out in the middle of the river.
“Video was taken right by our BLM Fairbanks District Office facing downstream. We’re not sure what it is. We’re letting you all be the judge.”
Most users are certain that the floating object is alive, with some viewers speculating that the 12-to-15-foot-long ‘creature’ is a distant cousin of the Scottish Loch Ness Monster.
However, a biologist who works for the Alaska Department of Fish and Game, said the object was most likely just a piece of rope.
He said: “It looks like it’s swimming but it’s actually stationary and just wading in the current.”