In this blog post, I’ll summarize the plot and share my thoughts on Jules Verne’s novel ‘Twenty Thousand Leagues Under the Sea’.

Plot

On July 20, 1866, the Hagin’s, sailing in the waters east of Australia, was attacked by an unidentified monster and wrecked. A few days later, on July 23, a fishing boat in the Pacific was stranded after being attacked by the same monster, and a series of unexplained shipwrecks began occurring all over the world.
News of these events reaches the U.S. Navy Department, prompting a meeting. Dr. Aronnax, author of ‘The Mysteries of the Deep’, asserts that the creature is a narwhal—a “unicorn of the sea.” Acting on his advice, Secretary of the Navy Hobson organizes an expedition to capture the narwhal and sends a letter to Dr. Aronnax inviting him to join the expedition.
Aronax, his assistant Conseil, and the whaler Ned Land, all aboard the ‘Lincoln’, set sail for the Atlantic under the command of Captain Parrott, where the monster is said to have appeared. Ned is skeptical of the claim that a whale could pierce iron plating, but Aronax counters that deep-sea creatures can withstand high pressure and might indeed be capable of doing so.
After a prolonged search yielded no results and the crew’s morale had plummeted, Captain Parrot was just about to give up when the monster appeared. The Lincoln fired upon it but failed to inflict significant damage; when the monster stopped during the pursuit, Ned threw a harpoon, but it bounced off. Moments later, Aronnax, Conseil, and Ned were suddenly swept into the sea by a column of water.
Exhausted from swimming, the group finds themselves, to their surprise, standing atop a massive machine, which they realize is a submarine. The submarine’s iron hatch opens, and several crew members emerge to usher them inside. Captain Nemo then appears and accuses them of attacking him. Aronnax learns that Nemo is a man who has renounced civilization and roams the world aboard his submarine.
The submarine’s name was the Nautilus, and Nemo tells the group that if they simply follow his instructions, he will allow them to tour the vessel. Thanks to Nemo’s hospitality, Aronnax and his companions tour the interior—including the dining room, library, and museum—and receive an explanation of the Nautilus’s structure and power source. Nemo reveals that the Nautilus is powered by electricity, with most of its energy derived from the sea.
While Nemo is away, Ned resolves to escape from this prison-like vessel. Suddenly, a steel panel on the side of the submarine opens, revealing a fantastical underwater landscape beyond the glass window, leaving Aronnax, Conseil, and Ned speechless with wonder. Nemo invites them to join him on a “hunt” beneath the sea—a hunt that takes place not in a forest on land, but in an underwater forest.
From the experience of diving in wetsuits to hunt sea otters, to scenes of resupplying provisions and holding funerals for sick crew members, to the beautiful sight of the sea turning milky white with translucent creatures when they surfaced at night—Aronnax and his companions have a special experience every day.
The Nautilus observes various parts of the world from beneath the sea, including pearl diving near the island of Ceylon (India), a voyage through the Mediterranean and passage through the Arabian Tunnel in the Red Sea, a visit to the legendary Atlantis, an expedition to Antarctica, and the planting of a flag bearing the initials of its name. An incident in Ceylon, where Ned and Nemo rescue an Indian man threatened by a shark during pearl diving, becomes an opportunity for Aronnax to see a different side of Nemo.
During the journey, near the Bahamas, a swarm of giant squids attacks the Nautilus, killing one of the crew members, and Nemo is overcome with grief. While this leads Aronnax to feel a sense of humanity toward Nemo, Ned’s dissatisfaction only grows. Eventually, Ned attempts to escape on several occasions.
One day while sailing across the Atlantic, shells land near the Nautilus, and the crew seizes the opportunity to attempt an escape. However, upon spotting a warship, Nemo rams the Nautilus into it, sinking the vessel. Having witnessed the drowning of many sailors, Aronnax feels deep anger toward Nemo. Nemo weeps bitterly while looking at family photographs in his cabin and remains out of sight for several days.
Aronnax and his companions eventually escape the Nautilus by boat, and after witnessing a massive whirlpool engulf the vessel, Aronnax loses consciousness. Some time later, after being rescued on the Lofoten Islands in Norway, he completes his account of the ten-month journey aboard the Nautilus. Finally, gazing out at the horizon across the sea, he recalls Nemo and the Nautilus.

Review

‘Twenty Thousand Leagues Under the Sea’ is a novel by the 19th-century French author Jules Verne, set primarily against the backdrop of a maritime adventure that reflects the influence of his hometown, the port city of Nantes. Verne wrote numerous works, and it is widely known that ‘Around the World in Eighty Days’, published in 1873, is the best-selling of his masterpieces.
The novel can be broadly divided into three parts. The first covers the process by which Dr. Aronnax and his companions discover the Nautilus and board the submarine; the second details the events they experience while traveling the world’s oceans aboard the Nautilus with Captain Nemo; and the third describes their escape from the Nautilus and the catastrophic conclusion.
The first part unfolds with a tense sequence of events: reports of an unknown sea monster, the expedition’s departure, an encounter with the monster, and the three men who fall into the sea and are dragged into the submarine. The second part unfolds with a succession of scenes that stimulate the reader’s imagination—such as the underwater landscape and ecology, pearl diving, a visit to Atlantis, and an expedition to Antarctica—while Captain Nemo’s humanity and mystery are gradually revealed through Aronnax’s perspective.
The third part leads to a cataclysm, marking an emotional turning point in the story. Aronnax feels anger toward Nemo’s actions, but in the end, witnessing the scene where Nemo and the Nautilus meet their fate, he experiences compassion and complex emotions. This shift dramatically reveals the characters’ psychological states and moral conflicts.
Although the novel’s plot appears simple, its core lies in the depiction of the underwater world, which stands in contrast to the real world. Unlike the cities forged by the machinery of civilization, the depths of the sea are portrayed as a space brimming with nature’s abundance and mystery. The author depicts this landscape with great detail and breadth, creating a unique atmosphere that blends science-fiction imagination with lyrical naturalism.
Ultimately, ‘Twenty Thousand Leagues Under the Sea’ holds significance beyond that of a mere adventure story. By exploring themes of humanity, civilization, revenge, and compassion against the extreme backdrop of the ocean depths, it simultaneously evokes a sense of wonder and raises ethical questions for the reader. Aronnax’s account serves as both a testimony to his experience and a reflection on the lingering emotions left behind by Nemo and the Nautilus.