In this paper, we concentrate on the factors that led to Portugal’s superiority at sea during the age of exploration. In the first part we will focus on Portugal’s historical background and its important factors which were necessary in order to achieve such an outstanding position in the world. Further, an overview about navigation and cartography techniques follows including a description of a number of problems medieval navigators were confronted with. The subsequent part of the paper demonstrates the motivating forces for the development of seapower and compares the shipbuilding technology of Portugal and that of the most advanced civilization at that time. The last section deals with the impacts of the revolution and the expeditions to West Africa and India.