Amerigo Vespucci!
Expeditions
At the invitation of king Manuel I of Portugal, Vespucci participated as observer in several voyages that explored the east coast of South America between 1499 and 1502. On the first of these voyages he was aboard the ship that discovered that South America extended much further south than previously thought.
The expeditions became widely known in Europe after two accounts attributed to Vespucci were published between 1502 and 1504. In 1507, Martin Waldseem�ller produced a world map on which he named the new continent America after the feminine Latin version of Vespucci's first name, which is Americus. In an accompanying book, Waldseem�ller published one of the Vespucci accounts, which led to criticism that Vespucci was trying to upset Christopher Columbus' glory. However, the rediscovery in the 18th century of other letters by Vespucci has led to the view that the early published accounts, notably the Soderini Letter, could be fabrications, not by Vespucci, but by others.WIKI
http://en.wikipedia.org/wiki/Amerigo_Vespucci
His contribution to the Craft of Navigation is probably more important than his Contribution to Exploration!