"20,000 Leagues Under the Sea" is a science fiction novel written by Jules Verne, published in 1870. The story follows Professor Aronnax, his servant Conseil, and a Canadian whaler named Ned Land as they embark on a journey to capture a mysterious sea creature. Instead, they encounter the submarine Nautilus, commanded by the enigmatic Captain Nemo. As they travel beneath the ocean, the characters experience various underwater adventures, exploring marine life and shipwrecks. The novel explores themes of exploration, technology, and the conflict between man and nature, making it a classic in the genre of adventure literature.