I can see the parallels with the Greek myths, which likewise saw the underworld as fierce and menacing. The more Northern pantheons like the Norse and Celts saw the sea as equally dangerous.







Shaver was a rather odd character, and today we may have diagnosed him as paranoid and maybe schizophrenic. He wrote about his degererate underground race, the Deros, as using mind rays to control humans on the surface, beaming messages into their minds. He also offered detailed sado-masochistic accounts of the torture and rape of their victims (which were duly edited out of his published stories).

I think there may be something in the connection you suggest, or it may be even more direct. Shaver was writing just after the great American scare of Japanese invasion, at a time when the Japanese were caricatured in the US as small, cruel, devious, and degenerate, just like Shaver's Deros.