These observations partly apply here. The subtitle of the present book is An Underwater Tour of the World, so in good travelog style, the Nautilus’s exploits supply an episodic story line. Shark attacks, giant squid, cannibals, hurricanes, whale hunts, and other rip-roaring adventures erupt almost at random. Yet this loose structure gives the novel an air of documentary realism. What’s more, Verne adds backbone to the action by developing three recurring motifs: the deepening mystery of Nemo’s past life and future intentions, the mounting tension between Nemo and hot-tempered harpooner Ned Land, and Ned’s ongoing schemes to escape from the Nautilus. These unifying threads tighten the narrative and accelerate its momentum. Other subtleties occur inside each episode, the textures sparkling with wit, information, and insight. Verne regards the sea from many angles: in the domain of marine biology, he gives us thumbnail sketches of fish, seashells, coral, sometimes in great catalogs that swirl past like musical cascades; in the realm of geology, he studies volcanoes literally inside and out; in the world of commerce, he celebrates the high-energy entrepreneurs who lay the Atlantic Cable or dig the Suez Canal. And Verne’s marine engineering proves especially authoritative. His specifications for an open-sea submarine and a self-contained diving suit were decades before their time, yet modern technology bears them out triumphantly. True, today’s scientists know a few things he didn’t: the South Pole isn’t at the water’s edge but far inland; sharks don’t flip over before attacking; giant squid sport ten tentacles not eight; sperm whales don’t prey on their whalebone cousins. This notwithstanding, Verne furnishes the most evocative portrayal of the ocean depths before the arrival of Jacques Cousteau and technicolor film. Lastly the book has stature as a novel of character. Even the supporting cast is shrewdly drawn: Professor Aronnax, the career scientist caught in an ethical conflict; Conseil, the compulsive classifier who supplies humorous tag lines for Verne’s fast facts; the harpooner Ned Land, a creature of constant appetites, man as heroic animal.