Micronesia and the North Pacific Gyre

From Conquering The Pacific: An Unknown Mariner and the Final Great Voyage of the Age of Discovery, by Andrés Reséndez (HarperCollins, 2021), Kindle pp. 120-121:

The second arrow shot across the Pacific, the Villalobos expedition of 1542–43, essentially retraced the previous track and confirmed that the best way to sail from the Americas to Asia was indeed via a straight path across the ocean just north of the equator. Wind maps of the North Pacific show a broad westward-moving band of winds (and currents) between five and twenty-five degrees of northern latitude, connecting Mexico and the Philippines. Wide, continuous or nearly so, and quite regular all year round, this portion of the North Pacific Gyre amounts to a veritable highway across the ocean, far easier to locate and navigate than the northern portion for the return trip, as we shall see.

Just as earlier Atlantic navigators had used the Sargasso Sea to orient themselves, the Saavedra and Villalobos expeditions began identifying some of the Micronesian—that is, tiny—islands on the way to the Philippines. To get a sense of the difficulty, we need to consider that all the Micronesian islands add up to 271 square miles, or a quarter of Rhode Island, the smallest state in the United States, but are scattered over a patch of the Pacific that is roughly the size of all the contiguous states in the Union. Still, the Saavedra expedition was able to sight a group of low-lying atolls they grandly called “las Islas de los Reyes,” or “the Islands of the Kings” (probably the present-day Faraulep Atoll at 8.6 degrees of northern latitude). More promisingly, the Villalobos expedition spotted a small island with many coconut palms and thickly inhabited (likely the present-day island of Fais at 9.7 degrees of northern latitude). The captain called it Matalotes because, as they passed, some of the islanders paddled toward the vessels and called out in cheerful Spanish, “Buenos días, matalotes,” or “Good morning, sailors.” Somehow they had interacted with Spaniards before.

The Legazpi expedition pursued the same direct trajectory across the Pacific as the previous two voyages and benefited from the knowledge acquired up to then. The four vessels in Legazpi’s squadron remained safely inside the band of favorable winds and currents of the North Pacific Gyre, covering the six thousand miles between Mexico and the first Micronesian islands in record time. At every stage of the journey, the pilots—the very best in all the Spanish Empire—knew their precise location relative to the North Pacific Gyre because they estimated their latitude (north-south distance) every day.