[Source] One of the most interesting questions that many people have pondered over the centuries is whether our planet is at least partially hollow and inhabited. Most of us are familiar with the legendary stories about the Nazis who explored the polar regions of our planet and even created secret bases in Neuschwabenland, Antarctica. These rumors are based in fact, as Nazi Germany sent an expedition to Antarctica in 1938, claimed the territory of New Swabia, and immediately began building secret deep underground bases below the ice. German Navy Grand Admiral Karl Dönitz stated in 1943: "The German submarine fleet is proud of having built for the Führer in another part of the world a Shangri-La on land, an impregnable fortress."
The Nazis continually shipped men and material to the South Pole throughout the war years and defeated a "post WW2" attack by Allied forced in 1946, led by Admiral Byrd, who retreated in disgrace after suffering substantial damage and casualties (see Operation Highjump). U.S. Admiral Richard Byrd, upon his return from a massive military expedition to Antarctica in 1947, stated it was: "necessary for the USA to take defensive actions against enemy air fighters which come from the polar regions".