Italian explorer Francesco Sauro describes the importance of underground investigation. Every year hundreds of kilometres of caverns below the Earth’s surface are explored, with new discoveries in the underground world offering insights into the evolution of life. The thirst for geographic exploration, which drove intrepid voyagers like Charles Darwin and Alexander von Humboldt in the 18th century, now appears meaningless in the world of Google Earth, as satellites have surveyed every single square-metre of our planet’s surface... Read more on the web edition of The Guardian