After the first few chapters of Twenty Thousand Leagues build up the power and magnitude of the sea creature—presumed to be a massive narwhal—wreaking so much havoc, it turns out to be a submarine. This is an example of situational irony because characters and readers both anticipate the monster to be a living, breathing being but, in a plot twist, it is actually a man-made machine.
Aronnax’s descriptions of the creature before he knows it’s a submarine add to the irony, as he compares the creature to a machine (foreshadowing the big reveal):
Notwithstanding the distance, and the noise of the wind and sea, one heard distinctly the loud strokes of the animal’s tail, and even its panting breath. It seemed that, at the moment that the enormous narwhal had come to take breath at the surface of the water, the air was engulfed in its lungs, like the steam in the vast cylinders of a machine of two thousand horse-power.
While Aronnax never goes on to share the actual horse-power of the Nautilus, his fanciful description of the creature as a machine does capture the might of the submarine that he will soon get to know. The irony, of course, is that he had no idea such a machine could even exist since, until that point, Captain Nemo kept his innovations to himself.
When Aronnax finds himself trapped in an unknown submarine and handled roughly by masked men (who turn out to be part of Captain Nemo’s crew), he uses a simile to express his outrage:
“By the pluck!” he fumed. “Here are people as badly off as the Scotch for hospitality. They are gentle as cannibals. And I shouldn’t be surprised if they were man-eaters. But I’ll be right there when they start to swallow me.”
By comparing the men to “cannibals,” Aronnax shows how flustered and frustrated he is by this situation. His comment that they are “as gentle as cannibals” is also an example of verbal irony—he is sarcastically commenting on how they are the very opposite of gentle.
This language also highlights Aronnax’s familiarity with the ideology of colonizers. At this period in time, Europeans would justify their imperialist inclinations by perpetuating the idea that indigenous people around the globe were nothing more than “cannibals” and “savages” (language that Aronnax goes on to use to describe the Papuan people with whom he comes in contact). With this simile Aronnax displays a lack of self-reflection—it was he and his crewmates who hunted down the Nautilus, after all, and attacked it first. If anyone could be compared to cannibals (or other violent descriptions), it should be them.
It becomes clear over the course of the novel that much of Captain Nemo’s character is centered on the fact that he’s from a colonized nation and wants to be free from the violence of imperialism. The situational irony comes in as readers witness Captain Nemo perpetuate the very violence that he seeks to be free from several times.
For example, Nemo holds Aronnax, Ned, and Conseil captive for months, imposing his will on them at all times. He also spends his time “discovering” places unexplored by humans, documenting and categorizing deep-sea flora and fauna, a process not dissimilar to the colonizer’s attempt to control and categorize the people of foreign nations.
The irony of his violent impulses comes across well in the scene in which he introduces himself to his three captives, explaining why he lives the way he does:
"The sea does not belong to despots. Upon its surface men can still exercise unjust laws, fight, tear one another to pieces, and be carried away with terrestrial horrors. But at thirty feet below its level, their reign ceases, their influence is quenched, and their power disappears. Ah! sir, live—live in the bosom of the waters! There only is independence!"
Here, Nemo says the sea is free from despots, not realizing that he has become one in the very act of taking these three people prisoner. The “independence” he speaks of is reserved solely for him and not for anyone else. It is certainly ironic that Nemo both identifies with the oppressed and also embodies the violent urge to control people (and the natural world).
Over time aboard the Nautilus, Aronnax comes to enjoy Captain Nemo’s company and stops desiring to escape, an example of situational irony. While readers would expect Aronnax to join Ned and Conseil in attempting to leave the submarine (and their position as prisoners), he continues to want to stay. This comes across most clearly in moments when Ned and Conseil come up with escape plans and Aronnax feigns interest while revealing his ambivalence to readers, such as in Part 2, Chapter 8:
A sad day I passed, between the desire of regaining my liberty of action and of abandoning the wonderful Nautilus, and leaving my submarine studies incomplete. What dreadful hours I passed thus! Sometimes seeing myself and companions safely landed, sometimes wishing, in spite of my reason, that some unforeseen circumstance, would prevent the realisation of Ned Land’s project.
Aronnax himself acknowledges the irony of wanting to stay aboard the submarine (calling it a desire he had “in spite of my reason”), but it doesn’t make him let go of his love for the “wonderful Nautilus.” Caught up in the excitement of research, Aronnax doesn’t care that he has been cut off from human civilization, repeatedly put in frightening situations, and imprisoned with little hope of escape. He no longer knows what is freedom and what is confinement.
The fact that a giant squid (or poulp) is the primary threat to the submarine’s safety is an example of situational irony. Aronnax, Ned, and Conseil originally set sail on the Abraham Lincoln to find a massive, threatening sea creature only to discover that it was man-made technology (the submarine), leading them to give up their belief in such a powerful creature. In their minds, civilization had won and sea creatures were no longer a threat. Their views then have to change again when the squid proves to be a genuine threat to the Nautilus.
Aronnax’s description of the battle communicates the power of the squids:
Ten or twelve poulps now invaded the platform and sides of the Nautilus. We rolled pell-mell into the midst of this nest of serpents, that wriggled on the platform in the waves of blood and ink. It seemed as though these slimy tentacles sprang up like the hydra’s heads. Ned Land’s harpoon, at each stroke, was plunged into the staring eyes of the cuttle fish. But my bold companion was suddenly overturned by the tentacles of a monster he had not been able to avoid. Ah! how my heart beat with emotion and horror!
Ned is known for being a master harpooner, yet here he is bested by the squid, which Aronnax even calls “a monster,” harkening back to the language from the start of the book. That Aronnax’s heart beats “with emotion and horror” also shows how powerful the squids are in the face of unparalleled underwater technology. Just as Captain Nemo and Aronnax are feeling like they have full power over the sea, a creature (that is not mythical but, in fact, a normal part of the ocean) threatens them, proving that nature still has power over technology.
