Having a meaningful title, "Twenty Thousand Leagues Under the Sea" by Jules Verne is a science-fiction novel about a submarine, the Nautilus, a vessel conceived of long before any submarines were created.  In this novel only four leagues are mentioned; however, since 20,000 leagues equals fifteen times the radius of the earth, it is obviously a hyperbole used to express the extensive journey of Captain Nemo (whose name means "no one" in Latin) and his crew.

Since Verne was a Frenchman league is equal to four kilometers.  In Verne's novel a ship leaves Brooklyn aboard the ship Abraham Lincoln, but there is an accident in which the steering of the ship is damaged and the crew is thrown overboard.  Finding themselves stranded on the "hide" of a sea creature, the crew discovers that it is actually some type of vessel.  They are captured and brought aboard the Nautilus which has come from the depths of the sea (20,000 leagues = so deep that no one can find it).  This vessel has been constructed in secrecy and now roams the seas free of any land-based government (hence, Nemo's name since he belongs nowhere).