Journey to the Centre of the Earth, A by VERNE, Jules

The story involves a German professor (Otto Lidenbrock in the original French, Professor Von Hardwigg in the most common English translation) who believes there are volcanic tubes going toward the center of the Earth. He, his nephew Axel (Harry), and their guide Hans encounter many adventures, including prehistoric animals and natural hazards, eventually coming to the surface again in southern Italy. (Summary by wikipedia)