Portuguese navigator and explorer who discovered the westernmost point of Africa. In his quest to establish Portugal as a world leader in sea trade, Prince Henry the Navigator sent Dinís Dias, his captain, on an expedition to Africa in 1445. Dias reached the mouth of the Sénégal River, which the Portuguese later believed to be the western branch of the Nile, then went on to discover Cape Verde in western Africa. Dias named the area "Green Cape" because of its lush vegetation. On a later voyage, he sailed a caravel along the Sénégal.