Since Edmund Hillary and Tenzing Norgay first reached the summit of Mount Everest in 1953, conquering the world’s highest peak has been the goal of almost every serious mountaineer on the planet.
But this famous peak pales in comparison to two secret mountains, which are more than 100 times higher than Everest’s 8,800-metre summit, scientists have discovered.
Reaching heights of around 1,000 kilometers (620 miles), these continent-sized “islands” of rock dwarf anything else found on our planet.
However, confused adventurers can rest assured.
Scientists from Utrecht University have revealed that these gigantic peaks are not found on the surface of our planet.
Instead, they are buried about 2,000 kilometers (1,200 miles) beneath our feet.
Researchers estimate the mountains are at least 500 million years old, but they could date back to the formation of the Earth four billion years ago.
Lead researcher Dr Arwen Deuss says: “No one knows what they are and whether they are just a temporary phenomenon or whether they have been there for millions or perhaps even billions of years.”
Scientists have discovered two hidden mountains more than 100 times larger than Mount Everest (pictured)

These mountains (red) are hidden beneath the Earth at the boundary between the core and the mantle beneath Africa and the Pacific Ocean.

The Earth is made up of three layers: the crust, the mantle and the core, which were later separated into “inner” and “outer”. These mountains exist in the region where the outer core meets the mantle.
The two monstrous structures lie on the boundary between the Earth’s core and the mantle, the semi-solid area beneath the crust, beneath Africa and the Pacific Ocean.
Around it is a “graveyard” of sunken tectonic plates that have been pushed down from the surface in a process called subduction.
In a new study, researchers found that the islands are much hotter than the surrounding plates of the Earth’s crust and are many millions of years older.
Scientists have known for decades that there are enormous structures hidden deep in the Earth’s mantle.
This is possible thanks to the way in which seismic waves from earthquakes propagate through the interior of the planet.
When a powerful earthquake occurs, it rings the Earth like a bell, sending waves from one side of the planet to the other.
But when these waves pass through something dense or hot, they slow down, weaken, or reflect completely.
Thus, by listening carefully to the “tone” reaching the other side of the planet, scientists can get an idea of what lies beneath.

Mountains are called Large Low Seismic Velocity Provinces (LLSVP) because they slow down the passage of seismic waves. They are located in an area called the “slab graveyard,” where pieces of the crust sink toward the core. Because these slabs are colder, waves pass through them much faster.
Over the years, studies have revealed that there are two huge regions of the mantle where shock waves slow down dramatically, called Large Low Seismic Velocity Provinces (LLSVP).
Dr. Deuss says, “The waves slow down because the LLSVPs are hot, just as you can’t run as fast when it’s hot as you can when it’s colder.”
When waves pass through a much hotter region, they need to expend much more energy to pass through it.
Co-author Dr. Sujania Talavera-Soza says, “Just like when it’s hot outside and you go for a run, you not only slow down but you also get more tired than when it’s cold outside.”
That means the pitch of a wave passing through hot LLSVPs would be expected to be out of tune and quieter than other areas, an effect scientists call damping.
However, when the researchers examined the data, they were surprised to find a very different picture.
“Contrary to our expectations, we found little damping in the LLSVPs, which made the tones sound very loud there,” says Dr. Talavera-Soza.
“But we found a lot of damping in the cold slab graveyard, where the tones sounded very soft.”

Scientists used shock waves from earthquakes to create an image of the planet’s interior. They found that the waves passed slowly through the LLSVPs, but they were not as quiet or damped as they expected. This suggests that LLSVPs are very hot and have a large grain structure that must have formed over billions of years.
Chunks of rock in the crust cause great cushioning because they recrystallize into a compact structure as they sink toward the core.
This suggests that the mountains are made up of grains much larger than the surrounding slabs, since these would not absorb as much energy from the passage of seismic waves.
“These mineral grains don’t grow overnight, which can only mean one thing: the LLSVPs are much, much older than the surrounding slab cemeteries,” says Dr. Talavera-Soza.
On the low end, researchers estimate these underground mountains are at least 500 million years old.
But they could be much older, and could even date back to the formation of the Earth itself.
This goes against the traditional idea that the mantle is in a constant state of motion.
Although the mantle is not actually liquid, it moves as such for extremely long periods of time.
It was previously thought that the mantle would therefore be “well mixed” by the flow of currents.

Some scientists think LLSVPs formed when a Mars-sized planet called Theia collided with Earth 4.5 billion years ago. Part of Theia became a moon while the rest sank to Earth to form these structures.
But the fact that these structures are billions of years old shows that they have not been moved or altered by mantle convection, which means that the mantle is not well mixed after all.
Recently, scientists have suggested that LLSVPs could be the remains of an ancient planet that crashed into Earth billions of years ago.
Some researchers claim that the Moon formed when a Mars-sized planet called Theia collided with Earth, launching molten chunks of both planets into its orbit.
Since the Moon is much smaller than Theia’s suggested mass, this leaves the obvious question of where the rest of the planet has gone.
Researchers at the California Institute of Technology have suggested that the LLSVPs could be the remains of the Theia collision.
After running a series of simulations, the researchers discovered that a significant amount of ‘Theian’ material (about 2 percent of Earth’s mass) would have entered the lower mantle of the ancient planet Earth.
That would explain why these regions appear to be much denser, hotter and older than the surrounding slab cemetery.