Bartolomeu Dias or Bartolomeu Diaz (c. 1450-1500), Portuguese navigator, first to round the Cape of Good Hope, Africa. In 1481 he commanded a vessel in a flotilla that King John II of Portugal sent to the Gold Coast of Africa. Five years later, the king gave Dias command of an expedition to continue the exploration of the western coast of Africa, building on the knowledge of the 1482 expedition of Diogo Cam, who had sailed south to a point near Walvis Bay. Dias set sail from Lisbon in August 1487; in February 1488 he rounded the southern end of the African continent as far as the estuary of what was later named the Great Fish River. Dias thus opened a sea route from Europe to East Asia, which European merchants and statesmen considered essential to the prosperity of Europe. Vasco da Gama was able to pioneer the whole route to India, of which rounding the Cape of Good Hope was the key, thus completing the project begun by Henry the Navigator in the early 15th century.

On his return voyage, Dias stopped at the tablelands at the south-eastern end of Africa, which he named Cabo Tormentoso, or Cape of Storms. King John later gave it the name Cabo da Bõa Esperança, or Cape of Good Hope. Dias explored a total of about 2,030 km (1,260 mi) of previously unknown African coast. He returned to Lisbon in December 1488. In 1500 he sailed in an expedition under the Portuguese navigator Pedro Álvares Cabral and participated in the exploration of Brazil. Dias later perished in a storm off the Cape of Good Hope.