"In 1947 Byrd allegedly undertook another flight over the North Pole. This time, in a diary that didn’t surface until years later, Byrd recorded events as he flew into the earth, and encountered the inhabitants who live there.

Allegedly, he landed his craft and spoke with a representative of the city of Agartha (referred to as Ariana in some accounts), who reprimanded him for humanity’s recent invention of the atomic bomb, and warned that a dark age is to come if humans don’t shape up. Byrd was sent on his way, with instructions to bring this message back to the surface people."
https://exemplore.com/ufos-aliens/Hollow-Earth-Theory-and-Admiral-Byrds-Flight-to-Agartha

"Medal of Honor recipient Admiral Richard E. Byrd allegedly wrote his encounter with a lost civilization in Antarctica. According to Hollow Earth theorists, Byrd met ancient race underground in the South Pole."
https://medium.com/the-weird-closet/the-strange-hollow-earth-case-of-admiral-richard-byrd-7469a62264fc

"For years rumors have persisted that on his historic flight to the North Pole, Admiral Byrd flew beyond the Pole into an opening leading inside the Earth. Here he met with advanced beings who had a sobering message for him to deliver to Mankind at the Surface World."
https://anomalien.com/admiral-richard-e-byrd-encounter-with-a-lost-civilization-in-antarctica/

"In 1947, Admiral Richard E. Byrd led 4,000 military troops from the U.S., Britain and Australia in an invasion of Antarctica called “Operation Highjump”, and at least one follow-up expedition."
https://coolinterestingstuff.com/operation-highjump-declassified-pictures-ufo-evidence

"In 1946/1947 the US Government launched Operation: High Jump.
A War Fleet, complete with Aircraft Carriers, Destroyers and Attack Submarines, surrounded and invaded Antarctica.
After locating a powerful race of underground beings, they were attacked by UFO’s, ships sank and damaged, many killed, and told never to return armed again."
https://truedemocracyparty.net/2012/01/operation-high-jump-the-untold-ufo-war-in-antarctica-and-the-hollow-earth-theory-admiral-richard-e-byrd/

**Admiral Richard E. Byrd's Diary**
https://intothelight.news/knowledge-base/hollow-earth-aghartha/admiral-byrd/