Lidenbrock (Simile)
"His big eyes darted incessantly around behind imposing glasses; his nose, long and thin, was like a sharpened blade..." (5)
Axel on Cracking the Code (Simile)
"What amazement, what terror entered my soul! At first it was like being hit by a blow you didn't expect" (20).
Windmills (Simile)
"...nor even the great windmills on the ramparts, whose immense wings swelled up like a ship's sails in a strong sea-wind" (42).
The Journey and Axel (Metaphor)
Axel uses the metaphor of "[looking] down at the fathomless pit into which I was going to engulf myself" (86) to describe how he is going to test himself mentally through this journey; he will be forced to confront his fear and anxiety. What makes this metaphor even more impactful is that Axel will also literally be descending into an abyss.
A Diamond (Metaphor)
"I imagined I was travelling through a hollowed-out diamond with the rays disintegrating into a thousand dazzling lights" (108) is a stunning metaphor that Axel uses to explain how glorious and crepuscular the subterranean environment is.