Twenty Thousand Leagues Under the Sea is set in 1868, starting on land in New York City but mostly taking place in the Nautilus submarine across the world’s oceans. The mid-1800s were historically significant for a few reasons. First, this was a period of major advances in science and technology. Electricity was just starting to spread across the globe—powering new technologies—and Charles Darwin’s theories about the natural world were similarly becoming more popular. In Twenty Thousand Leagues, Verne builds on these discoveries and theories, introducing readers to the concept of a submarine (which, at that point, was something of a fringe technology) and having his characters categorize and document sea creatures à la Darwin.
The novel is also set during the peak age of imperialism. By the 1860s, much of the world had been colonized by imperial powers. The logic behind such imperialism was that (primarily) white European people were more “civilized” than indigenous people across the various continents and, as such, were entitled to their land and labor. Imperialist ideologies are present in Twenty Thousand Leagues in the ways that Aronnax refers to indigenous people as “savages” and “cannibals,” as well as in the ways that Aronnax and Captain Nemo alike seek to control the sea.
It is notable that the four main characters in the novel—Aronnax, Captain Nemo, Ned, and Conseil—are all from different countries: France, Belgium, Canada, and an unknown colonized nation, respectively. In some respects, Nemo is the outsider, as he is a stand-in for all colonized people. He states this quite directly to Aronnax after saving an Indian diver’s life:
“That Indian, sir, is an inhabitant of an oppressed country; and I am still, and shall be, to my last breath, one of them!”
On the other hand, Ned could be considered an outsider, as he is the only person who is not highly educated or financially well-off. All in all, the submarine is a microcosm of various social dynamics in the real world—nationalities, social classes, and races still exist, even under the sea.