Is there a hollow earth/subterranean worlds story that doesn’t feature some sort of natural light source to stave off the dark?

Morgo the Mighty takes place in a series of massive caverns located beneath the Himalayas. Each cavern is lit by a different degree and spectrum of light. The deeper one goes into the caves the brighter the light becomes. The explanation of where the light comes from is a bit ridiculous but probably no more so than the idea of a series of massive caves, teeming with life, located beneath the Himalayas.

If I ever do manage to do a rewritten and illustrated version of the story I plan to have the light originate from a different source than in the original novel. That source will probably be no less ridiculous than the source in the original.

McRory’s employer may not have said anything about how he planned to land the plane in Surrilana but he did make sure to bring lots of ammunition on the expedition. That proves handy later.

Morgo the Mighty takes place in Surrilana, a vast cavern – series of caverns actually – beneath the Himalayas. Our protagonist, Jerry McRory, is hired to fly a plane through the mouth of a cave in the side of one of the mountains. While McRory believes that his employers claims of a great treasure are nonsense he never stops to ask what seems like a more obvious question – “Where I going to land this plane in a cave?”