Hans and the Lidenbrocks are beset with difficulties and life-threatening dangers throughout the book. Their journey leads them through many hostile environments, and they are frequently forced to choose between personal safety and scientific discovery. Axel repeatedly suggests turning back—and did not, in fact, want to go at all—though he notably never abandons the group for fear of danger. Despite Axel’s protests, the professor disregards the dangerous nature of their mission and pushes the group forward. Fortunately, Hans’s ingenuity and level head help the group survive the journey. Their collective bravery and perseverance is rewarded, and they are able to witness geological features, fossils, and even living plants and animals—including a giant humanoid—entirely unknown to the rest of the world. In the end, the trio's understanding of the world is enriched, and the professor has a collection of fantastic stories to tell.

Axel and the professor have different outlooks on life, and their conflicting views on the value of their mission are a recurring source of conflict. Timid, doubtful, and pessimistic, Axel doesn’t believe that the journey will be a success. The professor, however, exemplifies unceasing faith from the start; there is no doubt in his mind that he and Axel will be able to decipher the mysterious parchment, and he never once questions the wisdom of embarking on such a dangerous journey, even on short notice. The professor largely dismisses the obstacles the group encounters—including dangerous gases, nearly running out of water, and being accidentally separated—and remains certain that they will be able to explore the wonders beneath the earth’s surface. By contrast, Axel, who was hesitant from the beginning, continually suggests that they turn back. Although the group does manage to find their way out of each perilous situation they encounter, he remains unconvinced of their survival and cannot see the value of risking their lives on this fruitless venture.

Upon their descent into the earth, the adventurers encounter natural phenomena that defy belief, including prehistoric creatures, enormous fungi, and evidence of mysterious humanoids. The professor is both a geologist and an observer of the world around him; therefore, readers might expect him to be especially in tune with or respectful of nature. However, his single-minded personality—coupled with his overwhelming desire to achieve his goal—ultimately outweighs any reverence he may have for the natural world. While he doesn’t outright seek to destroy nature, the professor isn’t always adept at taking cues from his environment. His cavalier attitude is particularly evident in his decision to blow up the rocks that block the group’s path—despite the potentially cataclysmic danger of doing so. He is confident in his ability to defeat any and all obstacles in his path, and his disregard for the power of nature ultimately puts the entire group at risk when the destruction of the rocks causes their raft to be swept away. If nature and man are in conflict throughout the story, then it has to be said that nature ultimately wins when the group is forcefully ejected from the earth via a volcanic eruption.