In 20,000 Leagues, Verne lets us explore a fascinating, mysterious world—the ocean depths—thanks to a revolutionary piece of technology: the Nautilus. There are thrills; men fight squids, men fight sharks, and men fight each other. There are also scientific marvels galore; we read about electricity guns, frogman suits, super-powerful underwater vessels, and more.
Everything in 20,000 Leagues may seem less innovative these days, what with our nuclear submarines and all. But in Verne's day, a lot of this technology was downright prophetic.
Plus, though Verne did "explore" space in his earlier book, From the Earth to the Moon, this novel proves that science fiction doesn't have to take place in outer space. Or in totally outlandish alternate universes. There's plenty of adventure to be had right here on earth, in our world's great oceans. We're sure David Attenborough would agree.