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
The Nautilus crosses the Mediterranean quickly; Arronax gets the feeling that Nemo is keen to return to the “open ocean” as soon as possible. The submarine is moving so fast that all hope of escape has been crushed, and Ned is severely disappointed. They pass over a bank of sand, and Conseil comments that this reef is like a “real isthmus joining Europe to Africa.” Arronax mentions that active volcanoes are diminishing, and that the Earth itself is cooling, to the point that it will one day be a “cold corpse beyond the power of artificial reviving.” At this point, everything on the planet will die out and it will become devoid of life, like the moon. Arronax notes that this will happen in “some hundreds of thousands of years.”
It is somewhat strange and haunting to read Arronax’s inaccurate prediction about the future of Earth. At the time the novel was written, large amounts of carbon dioxide were already being produced by fossil fuels, deforestation, and pollution, though no one knew that this was changing the Earth’s atmosphere. In a sense Arronax remains strangely prophetic—yet rather than life on Earth being threatened by cold, today it is threatened by heat.
Active
Themes
On February 18, the Nautilus reaches the Straits of Gibraltar. It speeds along a counter-current, and Arronax very briefly catches a glimpse of the ruins of the temple of Hercules. Only moments later, however, the submarine emerges into the calm waters of the Atlantic.
Arronax’s surreal, fantastical tour through the oceans is also at times a tour of human history and culture. It seems that even though Nemo aims to separate himself from civilization, traces of humanity are everywhere.