A strange object spotted during a sonar survey last year continues to baffle Swedish treasure hunters who have now dived the site.
The Ocean X Team normally look for shipwrecks in search of historic artifacts and antique wines, but decided to investigate their discovery, which some believe to be a UFO, more closely.
Located at a depth of around 85 meters (280 feet) in the Baltic Sea between Sweden and Finland, the rounded object is about 60 meters (195 feet) in diameter.
It is actually mushroom-shaped with the rounded part raised about 3 to 4 meters (10 to 13 feet) above the seabed. Leading to the object is a downhill trail more than 300 meters (328 yards) long which the divers described as a runway.
An egg-shaped hole at the top of the disc appears to be some sort of opening. Nearby are strange stone circle formations that look rather like small fireplaces and appear to be covered in soot.
“During my 20-year diving career, including 6,000 dives, I have never seen anything like this,” said team member Stefan Hogeborn in a statement. “Normally stones don’t burn.”
“I can’t explain what we saw, and I went down there to answer questions, but I came up with even more questions.”
According to the divers, the object has rounded sides and rugged edges.
“First we thought this was only stone, but this is something else,” said Peter Lindberg, co-founder Ocean X Team, in the statement. “And since no volcanic activity has ever been reported in the Baltic Sea the find becomes even stranger.”
“As laymen we can only speculate how this is made by nature, but this is the strangest thing I have ever experienced as a professional diver.”
The divers took samples which are now being examined by scientists, alongside expert analysis of sonar imagery to ascertain what the object might be.