The Baltic Sea has become a hotspot for shipwreck discoveries in recent years, with finds of vessels from centuries gone by shedding new light on the world’s most famous eras. Vello Mass, a researcher who pinpointed many of these ships, once said the boats languished at the bottom of the sea long before some of the sea’s most famous finds. He said: “There are hundreds of Viking ships out there, hundreds of old trading ships, hundreds of warships. “The Baltic’s an archaeological paradise.” Sweden has become synonymous with such finds, but shipwreck hunters found something very different near the Scandinavian country in 2012. Out searching for shipwrecks at a secret location between Sweden and Finland, the deep-sea salvage company Ocean Explorer captured an incredible image more than 80 metres below the water’s surface.
Team leader Peter Lindberg joked that at first glance, his crew thought they had discovered an unidentified flying object, or UFO.
He said: “I have been doing this for nearly 20 years so I have seen a few objects on the bottom, but nothing like this.
“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.”
Using side-scan sonar, the team found a 60-metre diameter cylinder-shaped object, with a rigid tail 400 metres long.
The disc-like shape was languishing 200 metres below the surface.
Mr Lindberg said: “We’ve heard lots of different kinds of explanations, from George Lucas’s spaceship – the Millennium Falcon – to ‘it’s some kind of plug to the inner world,’ like it should be hell down there or something.
“But we won’t know until we have been down there.”
The Head of Archaeology at Sweden’s Maritime Museums, Andreas Olsson, admitted he was intrigued by the pictures, but remained sceptical about what it could be.
The reliability of one-side scan sonar images was one of his main concerns, making it difficult to determine if the object is a natural geological formation or something different altogether.
He said: “It all depends on the circumstances when you actually tow the [sonar] fish after the boat.”
The object continues to baffle researchers.
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In 2019, Denis Asberg, who made the discovery alongside Mr Lindberg, told TV4 in Sweden: “There is a mountain, It could be 20-25 metres tall with a canyon in the middle, and below it there are a lot of loose rocks.
“The trail starts from here. Actually there are two trails. There is the one that leads to this large circle. Then there is another trail that leads to the second object which is about 200 metres from the round circle. We found it at the same time as the circle. But we had such focus on the circle that we have not had enough time to look at the other object. It is not circular.
“We were really surprised and puzzled. We were thinking what is it that we have found here. This is not a wreck. At that time we thought for sure there was a natural explanation.
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“We wanted to look into it some more and decided to keep this totally quiet. We contacted geologists, marine biologists and when they said they had never seen anything like this, of course more thoughts were triggered. It could be something really awesome that we’ve found.”
It is thought the object could be at least 140,000 years old after a university professor linked the mysterious disc to the Ice Age.
Volker Bruchert, an associate professor of geology at Stockholm University, said: “My hypothesis is that this object, this structure was formed during the Ice Age many thousands of years ago.”