'Twenty Thousand Leagues Under the Sea' is a science fiction novel by Jules Verne. The story follows Professor Aronnax, his servant Conseil, and a gritty harpooner named Ned Land. They get the chance to explore the ocean depths in the submarine Nautilus, commanded by the enigmatic Captain Nemo. Their journey brings them face to face with underwater marvels, dangerous sea creatures and fascinating scientific advances. However, they also struggle with being captives of the unpredictable Nemo, unable to return to their lives on land. The title refers to the distance travelled under the sea, not the depth reached.