Greatest European Explorer During The Age Of Discovery

From the end of the Viking Age to 1434 A.D., Cape Bojador on the north western coast of Africa was considered the edge of the navigable world as there was myths of sea monsters and burning seas beyond the cape, as the arabs called it "Abu Khatar", meaning "the father of danger." However, Henry the Navigator who was prince of Portugal at the time became fascinated with Africa and the source of the gold trade and stories of the legendary Prester John that lie to the south, so in 1434 he sent the first ever recorded european expedition passed Cape Bojador, initiating the Age of Discovery in Europe. For the next several centuries, europeans would go on to explore and conquer most of the world. Which european explorer do you think was the most significant during this era?

While Columbus may have exaggerated his accomplishment (and to be sure he had NOT reached Asia), he did cross the Atlantic and return with proof to report his findings to a Monarchy sufficiently motivated to begin what ethnographers today refer to as the "Columbian Exchange". There's only one such episode in history, so... Whatever you think of the man on a personal level, it's got to be Columbus in this category. (And note that my screen name is one of the most famous colonizers of North America from 5 centuries earlier!)