Born in Spain in 1475, explorer and conquistador Vasco Núñez de Balboa helped establish the town of Darién on the Isthmus of Panama, becoming interim governor. ... Ávila, reportedly jealous of Balboa, had him beheaded for treason in 1519. He a Spanish explorer, governor, and conquistador. He is best known for having crossed theIsthmus of Panama to the Pacific Ocean in 1513, becoming the first European to lead an expedition to have seen or reached the Pacific from the New World