Disclaimer: Tolkien made it dark in there, as much as he made the rest from Light.
Notes: A contrivance of sound... you need to read it aloud.
Legolas shivered, not from cold, he scarcely felt that... no, it was the awful weightiness of the mountain bearing down. He found his breathing shortening, like a marsh-mired hart ill-equipped to escape the hunter.
The others saw only impenetrable darkness, apart from when Gandalf made light blaze forth. Perhaps the dwarf could see as he did, but then Gimli delighted in this awful, catacomb-cold stone. The blackness chilled his fea, made his heart ill-easy. These never-ending stone galleries... Gimli exclaimed over their art till he fell silent, lost in awed reverence for the ancient masons, but Legolas’ heart ill-liked them.