Ahem, they would have gone through the straits at Gibralter to get to Peru where the mines were.
That is what one might think. Take the shortest route. However Peru and Sacramento can be reached the long way around and at that time it was a better known and easier, if longer, route. Getting around to the west coast by the Strait of Magellan or the Northwest Passage would have been quite a trial compared with the placid and scenic eastern route.