What Is the Baltic Sea Anomaly?

Finding something strange on the ocean floor isn't really a stretch. So when some Swedish divers, part of the Ocean X team, went treasure hunting, they found a couple of weird formations on the Baltic seafloor. "We had been out for nine days and we were quite tired and we were on our way home, but we made a final run with a sonar fish and suddenly this thing turned up," said team leader Peter Lindberg at the time.

In a radio interview, Lindberg gave a more detailed explanation of what the team saw. "It has these very strange stair formations, and if it is constructed, it must be constructed tens of thousands of years ago before the Ice Age," he said in a radio interview, according to NBC News. He also acknowledged that it could be a natural formation, like a meteorite.

And that was pretty much fair play to let our imaginations run wild. Were these parts of a crashed UFO? A shipwreck? The lost city of Atlantis? A meteorite? Whatever it was, it seemed to be utterly bizarre, a mystery.

Or, you know, not. While images showed the formation as a circular object with stair-like structures, that's actually an illustration. There's a sonar image of the anomaly. Still, scientists were skeptical that the sonar used was high resolution enough to capture the detail of the seafloor — not to mention, it was extremely doubtful the equipment was even functioning correctly [sources: Wolchover; Snopes].

So what are we left with? Volker Brüchert, a Stockholm University geologist, reportedly studied a few rock samples the divers picked up from the site. Initially, tabloids ran a quote from Brüchert that seemed to back up the Ocean X team's northern Baltic region discovery, but when asked about it, the scientist said no one had contacted him.

"It's good to hear critical voices about this 'Baltic Sea mystery,'" Brüchert said. "What has been generously ignored by the Ocean X team is that most of the samples they have brought up from the sea bottom are granites and gneisses and sandstones."

So the team found mostly run-of-the-mill stones that you would expect from the kind of glacial basin the Baltic Sea fills. Not exactly that wacky, considering that glaciers could've easily carried the rock from somewhere else [source: Wolchover].

And for that matter, glaciers could have carried big chunks of rock like the "formation" itself. Most experts agree that the structure is probably nothing close to man-made. It might be a glacial deposit. It could also be a rock outcropping, which would totally make sense on the ocean floor.

Either way, nothing we're seeing is either alien or even part of a lost civilization. But hey, don't let that discourage you: We could certainly use a bit of curiosity when it comes to ocean exploration.

This article was updated in conjunction with AI technology, then fact-checked and edited by a HowStuffWorks editor.