What exactly is the Baltic Sea Anomaly?

Did you know that less than 5 percent of the ocean has been explored [source: NOAA]? While we've successfully sent astronauts to the moon, we've only carried out two manned expeditions to the ocean's deepest point [source: Thar]. The first occurred in 1960 when two aquanauts descended to the depths. The second took place in 2012 when filmmaker James Cameron used his "Titanic" profits to fund the first solo dive [source: National Geographic].

The deep sea is a realm shrouded in mystery, ready to throw unexpected surprises our way — like the Baltic Sea anomaly, an unidentified and strange object discovered by Swedish treasure hunters at the Baltic Sea's bottom in 2011.

The Mysterious Baltic Sea Object

Finding something unusual on the ocean floor isn't all that surprising. So when a team of Swedish divers from Ocean X went on a treasure hunt, they stumbled upon a couple of strange formations on the Baltic seafloor. 'We had been out for nine days, feeling pretty worn out, and were on our way back, but we did one last scan with a sonar fish, and suddenly this object appeared,' said team leader Peter Lindberg at the time.

In a radio interview, Lindberg offered a more detailed account of what the team observed. 'It features these very odd stair-like formations, and if it's man-made, it must have been built tens of thousands of years ago, before the Ice Age,' he said during the interview, as reported by NBC News. He also acknowledged that it might be a natural formation, like a meteorite.

And with that, it was easy to let our imaginations take flight. Could these be remnants of a crashed UFO? A shipwreck? The lost city of Atlantis? A meteorite? Whatever it was, it certainly appeared to be completely bizarre, an absolute mystery.

Or maybe not. While the images depicted the formation as a circular object with stair-like features, this was actually an artist's interpretation. There is a sonar image of the anomaly. Still, scientists questioned whether the sonar had the resolution necessary to capture such detailed features of the seafloor — not to mention, there were doubts about whether the equipment was functioning properly [sources: Wolchover; Snopes].

Studying the Baltic Sea Rock Samples

So what are we left with? Volker Brüchert, a geologist from Stockholm University, was reportedly involved in analyzing some of the rock samples collected by the divers at the site. Initially, tabloids ran a quote from Brüchert that seemed to support the Ocean X team's discovery in the northern Baltic region. However, when asked about it, the scientist clarified that no one had actually reached out to him.

"It's refreshing to hear critical perspectives on the so-called 'Baltic Sea mystery,'" Brüchert said. "What the Ocean X team has conveniently overlooked is that most of the samples they retrieved from the seafloor are granites, gneisses, and sandstones."

The team mostly found ordinary stones that would be expected in a glacial basin like the Baltic Sea. It's not as odd as it seems, especially since glaciers could have easily transported these rocks from elsewhere [source: Wolchover].

Furthermore, glaciers might have also carried large chunks of rock that could explain the so-called 'formation' itself. Most experts agree that the structure is likely not man-made. It might just be a glacial deposit, or even a natural rock outcropping, which is a logical possibility on the ocean floor.

In the end, there's no evidence suggesting this is anything alien or part of a forgotten civilization. But don't let that stop your curiosity; the ocean remains an exciting frontier for exploration.