Vasco Núñez de Balboa is commonly credited as the first European to sight and reach the Pacific Ocean from the Americas, doing so in 1513 after crossing the Isthmus of Panama. His sighting on September 25–29, 1513 (sources differ on the exact day) led him to name the ocean the South Sea, which is today known as the Pacific Ocean. His expedition marked a historic milestone in proving the existence of a vast western ocean separating the continents of the Americas from Asia.