Britannica Educational Publishing 
Britannica Guide to Explorers and Explorations That Changed the Modern World [PDF ebook] 

There was a time when every voyage contained an element of the unknown. Today, however, the world spreads out before us carefully mapped and plotted. One must credit explorers with this transformation. Readers will devour these tales of explorers who have pushed geographic and personal boundaries, leaving virtually no corner of the globe off limits.