Prince Henry of Portugal spurred on Portuguese explorations of the coast of Africa and even farther. At the end of this answer, I'll provide some notes from a primary source regarding Henry and why he was so eager for his nation to pursue exploration by sea.
Going even beyond the coastal explorations of Africa, Vasco da Gama of Portugal was the first European explorer to reach India via a sea route. In 1497-1499, Vasco da Gama successfully sailed south around Africa and got to India by that route.
Now here's that bit about Henry of Portugal that I promised as an extra for you. Contemporary sources concerning Portugal's Prince Henry (called "The Navigator" because he sponsored sea voyages) stated Henry's reasons for promoting exploration: 1. Curiosity -- nobody had ever explored further down the coast of Africa before his sponsored voyages did.2. Commerce -- he wanted to discover possible trading partners in Africa.3. Reconnaissance -- he wanted to find out how far into Africa the power of the Muslims extended. (The Muslims were seen as enemies of Christian Europe.)4. Finding fellow Christians -- there was a legend that there was some great Christian prince yet in Africa from back in the days before Muslim conquests of North Africa.5. Conversions -- the Portuguese Catholics thought they could gain favor with God by converting non-Christians peoples to the Catholic faith.6. Destiny -- ultimately, Prince Henry thought it was in his stars to be the leadership force behind a great project like the exploration of Africa.