The story begins in May 1863, at the home of Professor Otto Lidenbrock in Hamburg, Germany. While leafing through an original runic manuscript of an Icelandic saga, Lidenbrock and his nephew Axel find a coded note written in runic script along with the name of a 16th-century Icelandic alchemist, Arne Saknussemm. When translated into English, the note reads:
SnæfellsjökullGo down into the crater of Snaefells Jökull, which Scartaris's shadow caresses just before the calends of July, O daring traveler, and you'll make it to the center of the earth. I've done so. Arne Saknussemm
Lidenbrock departs for Iceland immediately, taking the reluctant Axel with him. After a swift trip via Kiel and Copenhagen, they arrive in Reykjavík. There they hire as their guide Icelander Hans Bjelke, a Danish-speaking eiderduck hunter, then travel overland to the base of Snæfellsjökull.
In late June they reach the volcano and set off into the bowels of the earth, encountering many dangers and strange phenomena. After taking a wrong turn, they run short of water and Axel nearly perishes, but Hans saves them all by tapping into a subterranean river, which shoots out a stream of water that Lidenbrock and Axel name the "Hansbach" in the guide's honor.
Édouard Riou's illustration of an ichthyosaurus (which is actually more like a mosasaurus) battling a plesiosaurus.Following the course of the Hansbach, the explorers descend many miles and reach an underground world, with an ocean and a vast ceiling with clouds, as well as a permanent Aurora giving light. The travelers build a raft out of semipetrified wood and set sail. While at sea, they encounter prehistoric fish such as Pterichthyodes (here called "Pterichthys") Dipterus (referred to as "Dipterides") and giant marine reptiles from the Age of the Dinosaurs, namely an Ichthyosaurus and a Plesiosaurus. A lightning storm threatens to destroy the raft and its passengers, but instead throws them onto the site of an enormous fossil graveyard, including bones from the Pterodactylus, Megatherium, Deinotherium, Glyptodon, a mastodon and the preserved body of a prehistoric man.
Lidenbrock and Axel venture into a forest featuring primitive vegetation from the Tertiary Period; in its depths they are stunned to find a prehistoric humanoid more than twelve feet in height and watching over a herd of mastodons. Fearing they may be hostile, they leave the forest.
Continuing to explore the coastline, the travellers find a passageway marked by Saknussemm as the way ahead, but it has been blocked by a recent cave-in. The adventurers lay plans to blow the rock open with gun cotton, meanwhile paddling their raft out to sea to avoid the blast. On executing this scheme, they open a bottomless pit beyond the impeding rock and are swept into it as the sea rushes down the huge open gap. After spending hours descending at breakneck speed, their raft reverses direction and rises inside a volcanic chimney that ultimately spews them into the open air. When they regain consciousness, they learn that they have been ejected from Stromboli, a volcanic island located off Sicily.
The trio returns to Germany, where they enjoy great acclaim; Professor Lidenbrock is hailed as one of the great scientists of the day, Axel marries his sweetheart Gräuben, and Hans returns to his peaceful, eiderduck-hunting life in Iceland.
