The Aquatic Avenger travels (involuntarily) to the center of the Earth...
...to face a scientist from the surface who plans a horrible fate for him, specifically!
When this never-reprinted tale from Centaur's Amazing-Man Comics #10 (1940) was published, the superhero genre was only about a year and a half old.
There were few established tropes or rules so creatives like writer/artist Lew Glanzman were literally "flying by the seat of their pants" as they figured out what would work and what wouldn't!