The explorers encounter dramatic events, including massive storms and battles between prehistoric creatures. While crossing the subterranean sea, they are caught in a tempest and land on an unknown shore, discovering fossils and ancient lifeforms. Eventually, a volcanic eruption propels them back to the Earth's surface, emerging on Italy's Stromboli Island. Returning to Hamburg, they are celebrated as heroes, and Axel reunites with his beloved Gr?uben.
