The Greatest Explorers: The brave adventurers who risked their lives to understand how our planet works

Throughout history, a handful of unusually driven individuals have been inspired to explore the limits of the known world, inspiring us and changing our perceptions of our planet through their courageous adventures. What is it that makes these men and women risk their lives in desperate, often fatal efforts to discover distant and inaccessible places? Robin Hanbury-Tenison, himself one of the most distinguished explorers of the 20th century, looks at the greatest of their kind in history, b...