Some people believe that the Earth is hollow. Despite seismic testing, the verifiable existence of gravity, and geological testing to the contrary, this thousand-year-old Hindu myth has become a modern cover-up conspiracy. The fact that we're about to get a new movie about Nazis living inside the planet doesn't help. Or does it? We're at least done fighting them on the Moon, so there's that. I have no idea anymore.
There is a belief that not only is the Earth hollow, violating all known science on the matter but that a race of advanced humans lives inside it. This advanced race is often called "Agartha," with most residing in their capital city of Shamballa. The Dalai Lama is often believed to be their representative on the surface. Some believe that the Agarthans oversee and steer the development of the human race. As such, one of the major entrances to Hollow Earth is said to be in Tibet. Another entrance is said to exist at the base of the Great Pyramid of Giza.
Other common beliefs:
-Icebergs are composed of freshwater not because of snowfall's chemical makeup but because they're formed from freshwater lakes and rivers inside the Earth.
-No one has ever visited the north or south pole because the magnetic field surrounding the entrances to Hollow Earth confuses everyone into walking in circles.
-The government covers up satellite imagery.
-Pilots are forbidden from flying near entrances to Hollow Earth.
Buckle up because we're about to dive into the crazy.
There is a belief that an American has visited the Agarthans. Admiral Richard E Byrd of the US Navy is said to have flown his airplane into a cavern at the north pole that led to the inner Earth as written in a book called Phantom of the Poles.
He claimed to have flown "over soaring mountains, lakes, rivers, oceans, mammoth herds, and numerous cities." Not only that, Byrd described a star illuminating the inner atmosphere. He claimed his plane was intercepted by UFOs while flying in the atmosphere of Hollow Earth. His aircraft was escorted to a base where he met the ruler of Agartha. He was told he was allowed to enter Agartha due to his "high moral character." He was to serve as an emissary to Agartha from the surface regarding the dangers of nuclear war and the potential impact on the underground world.
In January of 1956, Admiral Byrd would later claim to have led an expedition to the south pole to explore Hollow Earth again via another entrance he claimed to know about. Naturally, this story was "suppressed by the secret government by buying up and destroying every copy" of the records of his expedition.
Another conspiracy theory regarding the Hollow Earth exists.. and it involves Nazis.
The conspiracy theory states that the Nazis colonized parts of Hollow Earth. They even created cities named Nue Deutschland, Nue Schwabenland, and Nue Berlin. How did they find the entrances? Aliens, of course.
The conspiracy theory states that in 1936 a UFO crashed in Freiburg, Germany. The SS captured the UFO under the direction of Heinrich Himmler. Hitler then ordered Nazi scientists to reverse engineer weaponry from the crashed alien spacecraft. A German scientist named Viktor Schauberger used the crashed UFO to design a flying saucer called "Vrill." This was controlled by the Vril society, a secret society devoted to the alien race called the Vrill-ya. This cult existed. The members of this cult were females that braided their hair to act as antennas to communicate with the alien race that they called the "Vrillians."
The Vril cultists gained unique insight into battle plans and secret routes through the Hollow Earth by communicating with the captured aliens from the UFO via telepathic hair braids. The Nazis, realizing defeat was inevitable, established a secret outpost in Antarctica called Station 211. This outpost was located near the Hollow Earth entrance and allowed the Nazi high command (including Hitler) to escape total defeat. Naturally, they are all biding their time until they can launch a Fourth Reich.
Alternatively, aliens did not tell the Nazis about Hollow Earth. Instead, they discovered secret texts from the lost civilization of Atlantis while exploring Tibet. You know, in case you believe in Atlantis but not aliens. It's like a choose-your-own-adventure novel.