In 1938, the Third Reich claimed New Swabia in Antarctica. The vessel called "Schwabenland" just before the outbreak of WWII,, headed into western Antarctica. This was done under the auspices of "securing Germany's whaling industry." This seemed feasible, given the fact that much could be manufactured from whales including nitroglycerin, margarine, and mechanical lubricants.
It was also apparently their goal to build a base there for operations, but the war broke out and much of these hopes were put on the backburner, but legends persist. The most persistent of those legends is that the Nazis reverse engineered a UFO that crashed in Germany. This legend says that the Germans took a lot of their important people, scientists and even concentration camp occupants to Antarctica to begin a secret base called "New Berlin." This legend gets even more boastful that there are 2 million citizens of this secret base there today.
Because of the stray UFO reports in the Antarctica area, even more excitement exists that such a thing is possible. (I'm not quite sure why popular culture likes the idea of the Nazis still being around unless it's just a desire to beat their asses twice.) In 1976, the Japanese reported 19 round objects that dove into the water near Antarctica on their radar screens, reportedly.
Supposedly adding credence to this concept was an interview done with a spy, Angel Alcazar de Velasco at his home near Madrid in 1998 before he passed on. He admitted that, not only did the Nazis have UFO technology, but that today's UFOs were attributed not to outer space, but to the Nazi ones from Antarctica.
In this interesting article, it discusses the 2012 legend that when Lake Vostok (large freshwater lake found under Antarctica) the Russians who discovered it might have also seen a huge golden swastica there, feeding the legend the Nazis went underground.
“It is thought that towards the end of the Second World War, the Nazis moved to the South Pole and started constructing a base at Lake Vostok. In 1943, Grand Admiral Karl Dontiz was quoted saying “Germany's submarine fleet is proud that it created an unassailable fortress for the Fuehrer on the other end of the world,” in Antarctica.
The legends persist and with the remoteness and unknown territory of Antarctica, it seems feasible that something could be hidden there and there is no creepier threat than Nazis out of time and place defying the odds. I expect we will see lots of future "insider witness" reports upcoming and a regular feed on this subject because of the high weird factor and exotic and magical attributes.