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
Captain Nemo invites Arronax to the island of Ceylon, which is known for its pearl fisheries. Nemo suggests they also hunt sharks, a prospect that terrifies Arronax. After Nemo leaves, Conseil and Ned come in, saying that Nemo has mentioned the pearl-fishing expedition to them, as well. Nervously, Arronax asks if Nemo gave any further information, and they reply that he didn’t. The men discuss pearls, and Arronax attempts to casually ask if Ned is afraid of sharks. Ned replies that as a harpooner, he hates sharks, but is not afraid of them. However, his words do not manage to assure Arronax.
The differing attitudes between Arronax and Ned toward the sharks suggest that, while Arronax may have the most expert knowledge about the natural world, deeply understanding the ocean is arguably something that cannot come from knowledge alone. Instead, it is based in interacting with the ocean in a direct, fearless manner the way Ned does as a harpooner.