Some details of the Nautilus as described by Verne are subject to interpretation and some may have been obscured in translation, but many are clearly stated. The largest portion of the information is found in the chapters titled "The Nautilus" (included in "The Man of the Seas" in incomplete translations), "All by Electricity", and "Some Figures". Additional information is scattered throughout the novel. Here's a summary of the details.

The Nautilus had a cylindrical hull 70 meters long and 8 meters wide. The double hull had tapered ends, as Nemo says to Aronnax, "like your cigar". (Nemo mentions the shape had already been adopted in London. This was the time of the "cigar ships".) The four bladed propeller was six meters in diameter with a pitch of 7.5 meters. When the Nautilus accidentally rammed the Scotia it produced a two-meter triangular hole. There was an ordinary rudder fixed to the stern and two diving planes fastened to the sides at the center of floatation. On the surface the Nautilus remained 90% underwater so its platform was 0.8 meter above the water. The platform had a structure of "medium height" with inclined sides, at each end. Forward was the wheelhouse with a 2-meter-square interior and four windows, nearly a foot thick, through which the pilot could see in all directions. Aft was the powerful light. A recession amidships held the longboat, described later as a rising enough above the deck to sit on. The platform also had a railing. Aronnax gives somewhat conflicting descriptions of the hull, first saying it is clearly metal, not looking like a living beast at all, but later describes the overlapping hull plates as resembling scales or a reptile's shell.

Verne provides considerable information about the interior, especially the forward end. There was a 7.5-meter air reservoir at the very bow. Moving aft, we find Aronnax's cabin (2.5 meters long), Nemo's cabin (five meters long). Next was the drawing room/salon/museum, ten meters long, six wide, and five high. This incredible room contained an organ, an art collection of great value and very large number of marine specimens. There was also a fountain made from a shell about two meters across. Finally, the salon had two large oblong windows protected by sliding panels. Moving aft, the next room was the library (five meters long) with 12,000 volumes, followed by the captain's dining room (also five meters). Both of these rooms were exquisitely furnished. There were watertight bulkheads between the dining room and the library and salon and the captain's cabin.

Near the midpoint of the boat the description becomes less clear. There was a central staircase leading to the deck platform and to the upper passage to the wheelhouse. There was also a ladder to the longboat, and somewhere near was the airlock used for underwater access. The central section had at least one and possibly two watertight bulkheads. The size of this central section is not given. Moving aft there was a small cabin (two meters long), and the galley (three meters) located between storerooms. Nearby was a bathroom with hot and cold taps. Next was the crew's berth room (five meters). There was one more watertight bulkhead and then the engine room, described as at least 20 meters long. It had a front part devoted to generating electricity and a rear part with machinery to turn the propeller.

Adding all the figures given accounts for 65 meters of the boat's total 70-meter length perhaps leaving five meters for the central section.

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