There seems to be some inspiration for this film taken from Jules Verne's "Journey to the Center of the Earth". Both feature an underground sea, in both the entrance to the Earth is close to the top of the Earth (Iceland in Verne's novel and Alaska in this film) and the escape from underground is unexpected and amazingly rapid.
This project was actually put together by two special effects men, Jack Rabin and Irving Block, who are listed as producers.
His role as Dr. Morley made Victor Kilian the star of this film. However, because he was blacklisted (due to Communist witch hunts of the period), his name did not appear in the credits.
Both the mountains mentioned, Mt. Lefat and Mt. Neleh, are fictional.