No-one is sure what lies beneath the frozen wastes of Antarctica's Wilkes Land
Some researchers believe it is the remains of a massive asteroid which was more than twice the size of the Chicxulub space rock which wiped out the dinosaurs.
But rival theories point to links with the Nazis in the Second World War, while some people claim it could be a massive UFO base or even a hidden portal to a mysterious underworld called Hollow Earth.
The “Wilkes Land gravity anomaly” was first uncovered in 2006, when NASA satellites spotted wild gravitational changes which indicated the presence of a huge object sitting in the middle of a 300 mile wide impact crater.
The object is so vast it causes gravitational anomalies in the region
To this day, scientists have no idea or way to discover exactly what is buried deep under this thick ice shelf
Secure Team 10
It stretches for a distance of 151 miles across and has a maximum depth of about 848 metres.
But the mysterious observations have long fuelled speculation and now UFO hunters Secure Team 10 have posted a YouTube video about the anomaly.
The video narrator says: “To this day, scientists have no idea or way to discover exactly what is buried deep under this thick ice shelf.
“This continent has been shrouded in a mystery of its own for years now.”
Scientists believe there is evidence of a massive impact crater
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Secure Team 10 suggested the Nazis built secret bases in Antarctica during the Second World War which were designed to be used by flying saucers.
They added: “There is some evidence of this coming to light in recent years, which images purporting to show various entrances built into the side of mountains, with a saucer shape and at a very high altitude.
“This begs the question: how would you enter these entrances without something that could fly and was the same shape as hole itself?”
Secure Team also suggested the US Navy led a mission to investigate the mysterious continent.
Was there an attempt to find the entrance to a secret world hidden underneath Earth
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This expedition was called Operation High Jump, which conspiracy theorists believe was an attempt to find the entrance to a secret world hidden underneath Earth.
However, the scientist who first spotted the anomaly believes it is actually evidence of a massive impact crater.
Ralph von Frese, who was a professor of geological sciences at Ohio State University when he discovered the "killer crater" in 2006, said: "This Wilkes Land impact is much bigger than the impact that killed the dinosaurs, and probably would have caused catastrophic damage at the time.
"All the environmental changes that would have resulted from the impact would have created a highly caustic environment that was really hard to endure. So it makes sense that a lot of life went extinct at that time."