LitCharts assigns a color and icon to each theme in Twenty Thousand Leagues Under the Sea, which you can use to track the themes throughout the work.
Scientific Discovery and Technological Innovation
Freedom vs. Constraint
Human Intelligence and its Limits
Exploration, Imperialism, and Conquest
Nature vs. Civilization
Summary
Analysis
Arronax has developed a burning curiosity about the source of Nemo’s resentment toward human civilization. Conseil has his own theory—that Nemo is a “misunderstood genius”—but Arronax remains bewildered by Nemo’s rejection of human society. The Nautilus is currently in the Indian Ocean, moving at a depth of between 50-100 fathoms. Arronax reflects that if he had not been such an ardent lover of the sea he would have felt bored by his time down there, but thankfully, he doesn’t. He is fascinated by the great array of marine life they pass on their journey. The light of the vessel attracts fish, though most swim away in fright shortly after.
Another question that the novel invites the reader to consider is whether Arronax behaves selfishly in not trying harder to free himself and the two other captives. As he points out here, the only reason why he can bear his state of imprisonment is because, strangely, it involves performing the pursuit that he loves most in the world. Yet the same is not true for Conseil and Ned, and Arronax arguably does not give enough consideration to this fact.
Active
Themes
The Nautilus spends the day of January 25 on the surface of the water. Arronax passes most of the day on the platform, fantasizing about encountering another vessel. In the early evening, he and Conseil spy a shoal of argonauts (a type of mollusk). The next day, the vessel is surrounded by a large group of terrifying sharks. When they pass creatures like this, Ned is overcome with an irrepressible urge to harpoon them. However, he never gets a chance—the Nautilus always speeds away. When the Nautilus enters the Bay of Bengal, they see a large number of corpses floating along the water. The water itself is a milky color, which Arronax explains to Conseil is the result of a large number of small worms within it.
The horrifying sight of the human bodies in the Bay of Bengal becomes a reminder of the terrible brutality of humanity (and colonizers in particular). The ocean is, of course, not free from violence or death, but there is something obviously and profoundly unnatural about the bodies floating in the water here, unlike the deaths that occur as part of the natural world.