For some reason, operation high jump is used by conspiracy theorist often to further their agenda. Admiral Byrd is in the middle of all this with many claiming that it he had a secret diary where he talked about a “hollow earth” and a “civilisation” within it.
A lot of people refer to a “Land beyond the poles” that Byrd allegedly wrote down
Article: From Admiral Richard E. Byrd’s diary February 19 ... Read even more