Some Nazi maps supposedly showed directions to reach an underground land presumed to be Agartha. This was stated in a letter from a German U-boat navigator, Karl Unger who also claims that a U-boat, U-209, made it to Agartha and confirmed that there is a kingdom within the earth.
https://image.nostr.build/a7c2832af1752960dad939da11dc7dc3453f70e5f07ed5871ed7e78dcfd47232.png

Source: x.com/redpillb0t/status/1837284360019386771