Nazi base in Antarctica from December 1938 plus associated myths
Firstly, the truth is that there was a small Nazi base in Antarctica from December 1938, established to facilitate vessels getting whale oil, vital for Germany.
However, Antarctica is perfect for the creation of myths and science fiction masquerading as fact. Over the years there have been rumours about Hitler, alive, escaping to Antarctica by U-boat, or his ashes being buried there in a huge underground facility, with whatever the authors of such myths want us to believe.
Some folk say that somewhere under Antarctica near to the end of WW2 the Nazis were on the point of creating very advanced aircraft, being helped in this endeavour by aliens. But Germany at that time had very little chance of providing fundamental materials for this because its capability to do so was severely weakened because its industrial facilities were being destroyed.
The known small base of the Nazis was destroyed in 1946, the Americans tested nuclear bombs above it in both 1946 and 1958.
But there are folk who continue to wish to believe that somewhere under Antarctica there is something going on. Clearly, Antarctica is a great setting for myths and science fiction, it being so meteorologically hostile to known life and it being so far away from civilisation. On YouTube there is enough about this to satisfy the student of history and the enthusiast of science fiction, though it is not presented as that.