Who was the first European to see the pacific Ocean from America's?

It is possible that it was seen by Europeans who visited China during the Middle Ages or during the travels of Marco Polo. Few would have recognized it or guessed at its size.

Vasco Núñez de Balboa was the first Spanish explorer to see the Pacific Ocean in 1513. One of the first explorers of the Americas mainland, he traveled by canoe across the isthmus of Panama in 1513.