The naturally occurring disk formed over the weekend in Westbrook, Maine on the Presumpscot River, drawing curious onlookers to investigate the unusual sight.
A drone video shows the gorgeous ice formation in all its glory, slowly rotating in what looks to be a slight bend in the river, with small eddies rolling by in the narrow passage not crowded out by the disk.
The formation in the Presumpscot River in Greater Portland, Maine, has drawn comparisons to an alien spacecraft, a carousel and the moon.
Footage of the formation gently spinning in the water has gone viral, with people around the world seemingly mesmerised.
It may look like the surface of the moon, but the phenomenon captured in the video above is a little closer to Earth.
The disc is about 300 feet in diameter, The Portland Press Herald reports.
Apparently, the ice disk is powered by the cold river's slow current.
Mark Battle, an associate professor of physics at Bowdoin College in Brunswick, said he's never seen anything like the Westbrook ice disk.
"The ducks were rotating on this big lazy Susan", Mr Mitchell said."... allowing the water to freeze more readily, while water moves faster around the edges, generating the spin".
"The Return of Wessie", she wrote of the ice disk. "It was a big duck-go-round".
Some tourists walked on the thin ice of the circle, posing and taking photographs, and one swimmer braved the -20C temperatures to dive off the disk and swim in the icy river water.
Maine's Presumpscot River is no longer just a run-of-the-mill waterway, thanks to a recently formed, enormous icy disk that's shocking locals with its size and continued counterclockwise rotation.