The Atlantic system of the early modern centuries was primarily the creation of European navigation, trade, and colonisation. Although the peoples of Africa and America were by no means passive spectators and played crucial roles in shaping the Atlantic system, it is the primacy of European agency that first needs to be addressed. Christopher Columbus' crossing of 1492 was the culmination of a period of Atlantic explorations rather than an isolated initiative, and those explorations were, in turn, the product of a number of structural conditions in late medieval Europe, conditions that made possible the careers of men like Henry the Navigator and Columbus himself. This article analyses the late medieval sources of the European dynamic involvement with the Atlantic. It also compares European conditions with those in Africa and America.