Nautilus is the fictional submarine captained by Nemo featured in Jules Verne's novels Twenty Thousand Leagues Under the Sea (1870) and The Mysterious Island (1874). Verne named the Nautilus after Robert Fulton's real-life submarine Nautilus (1800). Three years before writing his novel, Jules Verne also studied a model of the newly developed French Navy submarine Plongeur at the 1867 Exposition Universelle, which inspired him for his definition of the Nautilus.
Nautilus is described by Verne as "a masterpiece containing masterpieces". It is designed and commanded by Captain Nemo. Electricity provided by sodium/mercury batteries (with the sodium provided by extraction from seawater) is the craft's primary power source for propulsion and other services.
The Nautilus is double-hulled, and is further separated into water-tight compartments. Its top speed is 50 knots. Its displacement is 1,356.48 French freight tons emerged (1,507 submerged). In Captain Nemo's own words:
The Nautilus uses floodable tanks in order to adjust buoyancy and so control its depth. The pumps that evacuate these tanks of water are so powerful that they produce large jets of water when the vessel emerges rapidly from the surface of the water. This leads many early observers of the Nautilus to believe that the vessel is some species of whale, or perhaps a sea monster not yet known to science. To submerge deeply in a short time, Nautilus uses a technique called "hydroplaning", in which the vessel dives down at a steep angle.