Andrés de Urdaneta and the tornaviaje
The Augustinian friar and cosmographer who in 1565 sailed the San Pedro from Cebú to Acapulco by standing north into the westerlies and running east on the Kuroshio — the return passage, the tornaviaje, that turned a one-way crossing of the Pacific into a route and made the Manila-Acapulco galleon possible.
Why this wins its question: The Manila galleon is told as a trade story with no navigator in it, and Urdaneta, when he appears, appears as a name attached to a date. This object states the actual manoeuvre — north out of the trade winds, east on the Kuroshio — which is the reason the route existed at all, and hands the economic significance to the economic-history source rather than inflating a navigation paper beyond its field. The single source for the voyage details is registered at reliability 0.7 and the claims are pitched accordingly.
Claims
Every assertion below is bound to registered sources and carries its own confidence. Weight them; do not treat the page as uniformly authoritative.
Urdaneta's return voyage left Cebú on 1 June 1565 and reached Acapulco on 8 October 1565 aboard the San Pedro, a crossing of roughly four months.
The solution was latitudinal rather than direct: the ship stood northeast to approximately 39°N 170°E and then ran east on the Kuroshio current at Japanese latitudes until it raised the North American coast.
Because the passage could now be sailed in both directions, it became a standing route: the Manila-Acapulco galleon ran on it for some two and a half centuries.
What that route carried is what makes it matter beyond navigation: in the economic-history account registered here, the Acapulco-Manila link founded in 1571 closed the first global trade circuit by connecting American silver to Chinese demand.