A Journey into the Center of the Earth by Jules Verne

Journey to the Center of the Earth is a classic 1864 science fiction novel by Jules Verne (published in the original French as Voyage au centre de la Terre). The story involves a professor who leads his nephew and hired guide down a volcano in Iceland to the "center of the Earth". They encounter many adventures, including prehistoric animals and natural hazards, eventually coming to the surface again in southern Italy.