"Twenty Thousand Leagues Under the Sea" is a classic science fiction novel by Jules Verne, first published in 1870. The story follows Professor Aronnax, his servant Conseil, and the Canadian whaler Ned Land, who find themselves aboard the underwater vessel Nautilus, commanded by the enigmatic Captain Nemo. The novel explores themes of exploration, freedom, and the conflict between humanity and nature, as the crew journeys through the world's oceans and encounters various marine life and submerged marvels.