Twenty Thousand Leagues Under the Sea is unique in that it led to the creation of the genre that it now falls under—science fiction. Officially, Jules Verne is one of the founders of the roman de la science (or the novel of science), an early form of science fiction that went on to inspire many novels of the Golden Age of science fiction in the mid-1900s.
Few of Verne’s contemporaries were doing the kind of scientific world-building that he was doing. This world-building is evident throughout the novel in passages that focus on the mechanics of various technologies rather than advancing the plot, like the following:
It became necessary to renew the atmosphere of our prison, and no doubt the whole in the submarine boat. That gave rise to a question in my mind. How would the commander of this floating dwelling-place proceed? Would he obtain air by chemical means, in getting by heat the oxygen contained in chlorate of potash, and in absorbing carbonic acid by caustic potash? Or—a more convenient, economical, and consequently more probable alternative—would he be satisfied to rise and take breath at the surface of the water, like a whale, and so renew for twenty-four hours the atmospheric provision?
Here Verne shows readers that he is not lazily inventing new technologies for the sake of fiction but is doing so based on his understanding of concepts like chlorate, potash, carbonic acid, and atmospheric pressure. A thorough understanding of science and technology is just as important to him as character development and plot.
Twenty Thousand Leagues can also be considered an adventure novel in that the four main characters aboard the Nautilus (Aronnax, Captain Nemo, Ned, and Conseil) experience adventure after adventure: sharks, giant squids, ice traps, whirlpools, indigenous people defending their land, and more. This places Verne amongst Romantic writers who tell tales of impossible voyages and exploits. Still, as Verne was writing during the Realist literary period and paid attention to realistic details relating to science and technology, it could be argued that he belongs to this literary period as well.
