A Journey to the Center of the Earth by Jules Verne

classic 1864 science fiction novel by Jules Verne. The story involves a German professor Von Hardwigg who believes there are volcanic tubes going toward the centre of the Earth. He, his nephew Axel and their guide Hans descend into an extinct Icelandic volcano, encountering many adventures, including prehistoric animals and natural hazards, before eventually coming to the surface again in southern Italy.