Jules Verne

Twenty Thousand Leagues Under the Sea introduces Captain Nemo and the submarine Nautilus. The Mysterious Island later reveals more of Nemo's history, although it primarily follows castaways building a settlement.

No, working submarines existed before the novel appeared around 1870. Verne's achievement was imagining the Nautilus as a powerful, electrically driven vessel capable of sustained global travel beneath the sea.

The novel sends Professor Lidenbrock, Axel, and guide Hans into Iceland's Snæfellsjökull volcano and through an enormous subterranean world. Modern geology rules out such a habitable route through Earth's interior, but Verne built the adventure from the scientific debates and fossil discoveries of his era.

Yes. The 1872 novel belongs to Verne's Voyages extraordinaires and follows Phileas Fogg and Passepartout as they attempt to circle the globe within 80 days.