The main Characters in this novel are Captain Nemo, Professor Aronnax, Ned Land, and Conseil. Nemo (which is Latin for “nobody”) is an enigma. His age and nationality are unknown. But it is obvious that he is a gifted engineer, inventor, and marine biologist. Nemo has turned to the sea for his freedom and livelihood in response to some past horror, perpetrated upon his family by an oppressive government. He enjoys impressing his guests with his scientific prowess and genuinely seems to desire their company, but he cannot or will not confide in them. Nor will he abandon his intention to revenge himself on the passing ships of the colonial powers. Nemo is absolutely loyal to his crew and weeps when one dies. This is in sharp contrast to the quiet rage he feels when he attacks his enemies. The enigma of his character continues: is he a heroic revolutionary bent on promoting some international political cause or merely a demented pirate who ruthlessly destroys innocent people?
Ned Land is Captain Nemo’s chief adversary on board the Nautilus. Captain Nemo has granted his guests “the liberty of the ship,” but Land sees no “liberty” in being deprived of his freedom to come and go as he pleases. The 40-year-old harpooner is a man of action, not of scientific analysis, and he is used to the sea’s surface, not its depths. Ned Land tries repeatedly to escape from the Nautilus and to bring Conseil and Aronnax along with him, but they continually resist. His anger at constraint eventually forces his companions to become aware of the terms of their stay on the Nautilus. Paradoxically, Nemo is angered by Land’s actions yet sympathetic to his desire for freedom. It somehow echoes his own desire to escape from his self-imposed isolation.
Professor Aronnax is fascinated by the sea and all its life forms. Consequently, he is torn between staying with Nemo and learning the ocean’s secrets, or escaping with Ned Land. Until Nemo attacks and ruthlessly destroys a warship toward the end of the novel, Aronnax is intrigued by the Nautilus, the voyage, and his scientifically enlightening experiences. He remains awed by Nemo even after he finally decides that he must escape.
Conseil is intelligent and well educated, but his slavish devotion to Aronnax is excessive. In one scene, Conseil is shocked unconscious by a ray, but on regaining consciousness he scientifically classifies the animal that nearly killed him. Such behavior provides most of the rare humor in the novel.
The Characters generate Verne’s thematic interests. Ned Land single-mindedly pursues his freedom, while Aronnax and Conseil are not even aware that they are imprisoned. This brings up many interesting Questions about the nature of freedom and constraint. Nemo, himself, seems constrained by the world he has created in order to be free from outside political domination. Blinded by the marvels of the Nautilus and the ocean, Aronnax at first refuses to see that he has fallen under Nemo’s control and thus chooses imprisonment. Verne develops these ironies throughout the book.
Aronnax is obsessed with learning, and he seeks out scientific explanations for all the marvels he encounters on the voyage. Verne’s implication is that nature is knowable; it may be broken down into pieces and understood. Time and patient observation are all that humanity needs to unveil nature’s secrets. Thus, Aronnax keeps putting off the inevitable confrontation with Nemo so that he can learn just one more of the sea’s secrets.