The most common theme is Man versus Nature. In the book, Captain Nemo is somewhat of a control freak. He orders his crew around and tries to control everything, but one thing he can’t control is nature. And at certain times, nature presents itself as a challenge and proves that man is no match for its power. So, as much as Captain Nemo tries to control everything, nature proves that no matter how smart the man, how much technology he has, or how much force he uses, he can’t overpower nature. Another major theme in 20,000 Leagues Under The Sea is vengeance. Captain Nemo has a complicated past, and does not explain to anyone anything that has happened. He has an unexplainable vengeance for all mankind, but also has personal scores to settle. “Do you think I am ignorant that there are suffering beings and oppressed races on this earth, miserable creatures to console, victims to avenge?”