As they gained in experience, Portuguese seamen came to understand the North Atlantic not as a featureless expanse of water but as a space with peculiarities and clear signs. After sailing down the African coast and veering into the Atlantic for hundreds of miles, experienced pilots knew to look for the “Sargaço,” a floating mass of seaweed that exists to the west of the Cape Verde Islands between twenty and twenty-five degrees of northern latitude. Sargassum gathers in the becalmed areas close to the center of the North Atlantic Gyre, but contrary to myth, it is never thick enough to impede the movement of vessels. This “Mar de Sargaço,” as it became known, is quite simply a circular pool of warmer water held in place by the colder waters of the circling gyre. Its whereabouts offered a major clue to Atlantic voyagers. Having reached the Sargasso Sea, pilots sailed toward its northern limits to make sure that they had traveled sufficiently west and north to begin turning back toward Europe. From this increasingly familiar region in the middle of the Atlantic, the next target was the Azores, an archipelago of nine islands with deep-green valleys and volcanoes, which were still about nine hundred miles away from the Portuguese coast. As it was hard to make landfall precisely on one of these islands, sailors scanned the skies for another biological clue: “a seagull with red legs and other small birds.” It is no coincidence that the Portuguese explored and colonized the Azores in the 1430s and 1440s, the very years of experimentation with the volta do mar largo (or volta do Sargaço, as it was also known). From the Azores, the final stretch home was due east with favorable winds and currents.5
The North Atlantic Gyre was a major find, but it turned out to be only half of the story. In the 1470s, the Portuguese crossed the equator and stumbled on a second gyre in the South Atlantic. Once again, it was necessity that prompted the discovery of this second great wheel of winds and currents. As the Portuguese sailors could not make any further progress in their Atlantic explorations by staying close to the African coast, on account of the contrary elements, they were forced again into the open Atlantic, this time venturing in a counterclockwise direction, away from the continent until practically crossing the entire ocean and nearing the coast of Brazil. This detour enabled Portuguese vessels finally to catch the southward-moving Brazil current and eventually to double back east toward the tip of Africa. This volta around the South Atlantic—a maneuver similar to the one in the North Atlantic but longer—could take up to three months of sailing without sight of land.6
As early as 1500, Vasco da Gama, the great discoverer of the sea route from Portugal to India, penned a concise but unmistakable characterization of this second volta in the instructions that he left to his successor: “You should always go around the sea until reaching the Cape of Good Hope.” The recipient of such sound advice was Pedro Álvares Cabral, who followed da Gama’s words so closely that he drifted to the coast of Brazil, where he spent a few days before continuing eastward to India. Over the years, Portuguese seamen became familiar with the contours of the South Atlantic Gyre, as is evident in the so-called roteiros (derroteros in Spanish, rutters in English, routiers in French, and so on), or sailing instructions, occasionally penned by pilots to facilitate the task of future navigators. The South Atlantic roteiros alerted pilots to approach the coast of Brazil well to the south of Cabo de Santo Agostinho; otherwise they risked being knocked off course by the currents and pushed into the Caribbean, a disastrous turn of events that could delay the voyage by several months. Farther south along the Brazilian coast, pilots were warned to steer clear of the Abrolhos, a group of islands and reefs off the present-day state of Bahia. (“Abrolhos” comes from abre olhos, or “open your eyes” in Portuguese.) Once the fleets doubled back toward the tip of Africa, the only intervening land was Tristan da Cunha, a group of remote islands in the South Atlantic, first sighted in 1506, precisely during the early exploration of the South Atlantic Gyre.7
Sixteenth-century navigators probably did not understand that Earth’s rotation is what causes the ocean gyres. It would not be until the early nineteenth century when Gaspard-Gustave de Coriolis worked out the mathematics of the forces in a rotating system. Yet five hundred years ago, Portuguese pilots clearly referred to the ventos gerais (general winds) to distinguish them from more localized and variable winds. They also knew that these ventos gerais formed two rotating systems on either side of the equator. “When you have passed the equator and reached the general winds, you need to go with them for as long as possible,” a pilot named Bernardo Fernandes counseled in 1550, “because with them you will reach the Cape of Good Hope latitude.” Evidently seamen like Fernandes had a clear mental image of the gyres.8
If the Atlantic possessed two symmetrical wheels of currents and winds, it was reasonable to assume that the same was true in the Pacific. Magellan was likely the first to transfer this scheme from one ocean to the other. During his early years in Lisbon, he had the opportunity to learn about the Atlantic gyres. As a page and employee at the royal palace in the 1490s and early 1500s, Magellan received formal instruction in ocean navigation and rubbed shoulders with leading practitioners of the Atlantic voltas such as Vasco da Gama. In 1505, at the age of twenty-five, Magellan joined a fleet bound for India and thus had his first direct experience with the Atlantic gyres. He would go on to spend seven formative years in Asia, where his growing knowledge of the cutting-edge navigational technologies of his time proved decisive.9
Magellan’s 1518–19 proposal to the Spanish crown to cross the Atlantic and the Pacific assumed that both oceans had general winds. He downplayed the difficulties of navigating on the high seas and instead focused on finding a passage between the Atlantic and the Pacific. Remarkably, he succeeded at locating it, but getting through it turned out to be far more difficult than anyone expected. The famous strait at the southern tip of South America is narrow (barely a mile wide in some places), leaving crews very little room to maneuver while facing powerful contrary winds and enormous tidal changes. Magellan and his men thus had to wrestle with the elements for thirty-eight harrowing days, tacking back and forth until finally they emerged into a comparatively calm ocean that Magellan misleadingly named “el Mar Pacífico.” Thus began a new phase in this journey of discovery.10
Magellan’s trajectory across the Pacific seems preternatural when we consider the gyres: he sailed parallel to the Chilean coast while being pushed by favorable currents and winds and then veered west at around thirty degrees of southern latitude (close to the center of the South Pacific Gyre), thus catching the westward-moving band of winds and currents to get across the ocean. Today, World Cruising Routes recommends exactly such a course to cross the Pacific. Nonetheless, weeks after that first and very accurate turn, Magellan and his pilots decided to continue on a northwesterly path, eventually crossing the equator and overshooting their intended target, the Spice Islands, which lay in the Southern Hemisphere, as they knew well. In other words, Magellan’s fleet deliberately abandoned the South Pacific Gyre, entered the fickle Intertropical Convergence Zone along the equator, and ventured into another gyre that, as far as anyone knew at the time, might or might not have existed. Whatever the reasons for this perplexing northward drift, Magellan and his companions crossed the great ocean in one swoop for the first time in recorded history. In a single voyage, they gained knowledge about the general circulation of winds and currents in the Pacific which had required decades of painstaking work by the earlier navigators of the Atlantic.11
It is ironic that Magellan is known to posterity as the first circumnavigator of the world, as if he had somehow intended to show that the world was round or to pioneer a new commercial route. In reality, the Spanish Empire retraced Magellan’s tortuous trajectory only once more, in 1525–26. A youthful Urdaneta participated in that expedition and his opinion was clear. “The route from Spain to the strait found by Magellan is too long,” he wrote in his report, “and the strait itself is long, unpopulated, with a brief summer and a long winter, tempestuous, and very dangerous.” From then on
, all transpacific voyages departed from the western coast of North America and came to depend on the vagaries of the North Pacific Gyre.12
In this multigenerational effort to chart these global gyres, the next stage came in the form of two straight and elegant crossings of the Pacific. None other than Hernán Cortés spearheaded the first one. Barely nine months after he toppled the Aztec Empire, Cortés’s scouts reached Mexico’s west coast and established an outpost. “I have started building ships and brigantines to explore all the secrets of that coast,” this irrepressible conqueror of Mexico wrote to the Spanish monarch in 1522, “and this will undoubtedly reveal marvelous things.” Cortés considered leading an expedition from Mexico to the Spice Islands himself, but in the end named his cousin Álvaro de Saavedra Cerón as captain. The Saavedra expedition of 1527–28 proved calamitous. A storm in the middle of the Pacific dispersed the three ships in the fleet—two of which were never heard from again, as if swallowed by the ocean. The flagship La Florida struggled from the start because water kept pouring in through the keel close to a pin. The crew was forced to operate a pump day and night just to keep afloat. Remarkably, the Florida survived this initial challenge, withstood the mid-ocean storm, and overcame a second leak, eventually crossing by means of a direct path. The Florida benefited from favorable winds and currents all the way from Mexico to the Philippines and was able to cover impressive daily distances of between 90 and 140 miles, and as much as 250 miles if we are to believe one of the surviving logbooks.13
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.14
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.15
* * *
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. They had begun this painstaking work right at the departing port of Navidad, where, independently from one another, they measured the angle of the sun with respect to the horizon at noontime with their astrolabes and then used a declination table to correct for the sun’s altitude on the date of the measurement. The four surviving latitude readings at Navidad (19.5, 19.3, 19.25, and 19.5) are all within a third of a degree of the true latitude of 19.2 degrees. Considering the instruments and declination tables available in the sixteenth century, this was a negligible error and an extraordinary achievement. A third of one degree of latitude represents only twenty-three miles. Navigators would not have been able to spot a low island at a distance of more than ten or twelve miles, but at twenty-three miles, they would have been close enough to begin seeing floating vegetation, birds returning to their nests, and cloud formations indicating the proximity of land. In Columbus’s time, navigating by the altitude of the sun had been an esoteric technique that produced very mixed results. Fifty years later, navigating by the altitude of the sun had become, if not routine, at least more common and infinitely more reliable. Legazpi’s expert pilots were capable of great precision not only on land but also while standing on a heaving deck in the middle of the ocean. Here is a typical logbook entry: “Wednesday, December 6, 1564, we made 28 leagues following the same course,” wrote pilot Esteban Rodríguez two weeks after departure, “and I took the sun at thirteen degrees and three quarters.”16
Before the separation of the San Lucas from the rest of the fleet, the plan had been to go to the Philippines by way of the so-called “Islands of the Kings” (at nine degrees), “Matalotes” (at ten degrees), and a few others identified on earlier voyages. The distance between the coast of Mexico and these islands, however, was so vast that even extremely skilled pilots would have had a hard time estimating on what date, or even in what week, they had sailed far enough to be near them. The pilots were likely not to make landfall during an estimated window of time, and once that passed, they would not be able to tell if the islands they were seeking lay farther still, or behind them, or in some other direction.17
Anticipating such problems, the expeditionaries had agreed on a plan. “All will steer immediately to nine degrees of northern latitude, and then continue due west toward the Islands of the Kings and the Islands of the Corals, said to be at nine degrees,” Legazpi had explained, “and then go to ten degrees toward the Islands of Reefs and Matalotes.” Today this is called “parallel sailing” and consists of positioning the ships exactly in the latitude of the intended target well in advance and maintaining that latitude—correcting every day as needed—until reaching the destination. If they could just keep to a perfectly straight east-west line leading directly to the island that they were seeking, they would run into it sooner or later. But as the weeks went by, the pilots grew restless. Christmas came and went, New Year’s Day passed, and no island came in sight. They kept measuring the altitude of the sun, a daily ritual that at least yielded consistent results, even though “the pilots could not agree completely, because some took the sun at nine degrees and others at nine degrees and one-quarter . . . and each pilot tried to justify his results and explain why the others were wrong.”18
6
The Tiny Islands
After a month and a half, Legazpi and his men at last began encountering palm-fringed islands that seemed to rise out of nowhere. These jewels in the middle of the ocean were irresistible but extraordinarily treacherous. Some broke through the waterline, but others lurked just below the surface like deadly traps for passing ships. Enormous rings of sharp coral (atolls) formed placid azure lagoons teeming with fish, like visions from paradise. Yet attempting to stop there could easily turn disastrous.
Now known as the Marshall Islands, these volcanic columns rise straight up from the ocean floor. In the Cretaceous Period (145–65 million years ago), tectonic plates rubbed against one another, creating volcanoes that eventually broke through the surface. Yet since that time, the geologic activity had declined and the volcanoes receded. Thus, unlike the Hawaiian and other Pacific islands that lie in active volcanic zones, the Marshalls are constantly eroding and submerging, leaving ideal p
latforms for the coral to grow and form massive banks, perennially reaching for the surface as the islands themselves are slowly sinking. A mile-deep layer of dead coral, sand, and rock makes up the top portion of these columns. Close to the surface, the living coral often forms irregular rings enclosing shallow lagoons connected to the ocean through natural channels. Significantly, the coral tends to be steeper and more formidable in the direction that the currents—and thus the nutrients—come from. In other words, these coral islands are much harder to breach precisely in the direction from which the Spanish were approaching.1
A lookout on the flagship San Pedro spotted an island on January 9, 1565. A cannon shot signaled to the others to follow. After some hours, an elongated island came clearly into view. It was only about seven miles in length, “but the vegetation was lush and there were many coconut palms.” Legazpi’s three remaining vessels had been navigating at nine degrees in search of the Islands of the Kings, but the ships had accidentally drifted to ten degrees and serendipitously found this previously uncharted island (probably Mejit). After fifty days of continuous sailing, the expeditionaries were running low on water, and their urge to stop was overpowering. The three ships came very close to the island, “but it was completely surrounded by reefs, and we could not find a bottom.” Commander Legazpi and his companions persisted, going from one end of the island to the other, probing different places to find a mooring. In the course of this exploration, they sighted “a little village with houses and palm trees and islanders walking by the beach and others going around in canoes.” Throwing caution to the wind, the San Pedro approached the shore directly in front of the village, coming so close to it that the bowsprit (the pole at the front of the ship) touched land, and at that moment dropped anchor, “but could not find a bottom even though they had tied two ropes together.” The smallest of the three vessels, the San Juan, also approached the island until nearly touching it, and lowered an anchor. Miraculously, it held on to something, at a depth of 150 fathoms, or nearly nine hundred feet.2
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