The seas are full of the cast-offs of humanity, from tub toys that have fallen off container ships to boats swept away in storms to bottled messages deliberately set adrift. That flotsam has given oceanographer Curtis Ebbesmeyer insight into marine currents and how they have influenced the course of history. In this excerpt from his new book with writer Eric Scigliano, Flotsametrics and the Floating World: How One Man’s Obsession with Runaway Sneakers and Rubber Ducks Revolutionized Ocean Science, the authors explain how a vicious current has swept sailors from Japan all the way to the Americas many times over many millennia.

Storied drifters float forever on the seas of legend and, lately, the Internet, whether or not they ever existed: the drift bottles Aristotle's protégé Theophrastus supposedly tracked across the Mediterranean, Queen Elizabeth I's [official message-in-a-bottle opener, the] “royal uncorker,” the ghost ship Octavius and the Sydney’s phantom lifebelt [which supposedly drifted from Australia all the way to France], Daisy Alexander's [$6-million] will in a bottle, and Clyde Pangborn’s ocean-hopping plane wheel.

These tales have spawned legal battles, comics-page yarns, and endless dinner-table diversion. Other transoceanic drifters have had much larger effects. Some scholars and aficionados believe that ancient drifts brought more than just timbers, nails, and other inanimate flotsam to the Americas. They maintain that sailors, fishermen, or passengers occasionally survived the drift and settled in the Americas, injecting new cultural and genetic elements into its native societies. Some, such as the British-born zoologist and amateur epigrapher Barry Fell, go further. They maintain that Old World peoples—the secretive, sea-mastering Phoenicians in particular—actually sailed to the New World to trade and left their shipwrecked traces off shores as widely scattered as Beverly, Massachusetts, and Rio de Janeiro. Unfortunately, the native peoples of the Americas did not leave records of any such early contacts, so the epigraphers rely on inscriptions and other artifacts—often controversial, if not outright fraudulent—supposedly left by the ancient visitors.

It’s harder to argue that Asian voyagers likewise visited or traded with America, because distances across the Pacific are so much wider. And no flood of Asian artifacts has been reported in the Americas to match the European claims. Nevertheless, another contingent of scholars makes a compelling case for repeated wash-ups by Japanese castaways over the past six thousand years—sometimes with transformative effect on the native cultures of the Americas. The doyen of this faction is Betty Meggers, an eminent anthropologist at the Smithsonian Institution, who has advanced this inquiry for more than fifty years despite fierce resistance from her colleagues. In 1966, she published an authoritative account in Scientific American of how Japanese mariners drifted to Ecuador five thousand years ago. Since then she’s uncovered evidence—DNA, viruses that could only have originated in Japan, and pottery techniques found nowhere else—suggesting that ancient Japanese influence also reached Central America, California, Ecuador, and Bolivia.

Well into her eighties, Betty would present her latest research on Japanese diffusion each year at the Pacific Pathways meetings in Sitka, [Alaska]. Before the sessions, we and the other Pathways participants would board a boat to remote beaches near Fred’s Creek, an hour from Sitka. Between exclamations of delight at the telltale flotsam we discovered, Betty would share more of her findings. She approached the problem as a literal jigsaw puzzle, comparing pottery shards unearthed around the Pacific. The patterns on multiple shards excavated at Valdivia, Ecuador, and on Kyushu, the southernmost of Japan’s main islands, matched so well, she posited that a boatload of Japan’s indigenous Jomon people made the trip some sixty-three centuries ago. Other discoveries suggest that others first made landfall in California and San Jacinto, Colombia.

The impetus to this migration was one of the great cataclysms of humankind's time on earth. Few places are so prone to natural catastrophe as Japan, an island nation floating at the intersection of three tectonic plates, the Pacific, Eurasian, and Philippine. The slow but violent collision of these three plates produces spectacular earthquakes, tsunamis, and eruptions.

About sixty-three hundred years ago, a flyspeck island off southern Kyushu named Kikai exploded with a force that would dwarf all the more famous volcanoes that have since erupted around the world. Kikai weighed in at 7 on the standard volcanic explosivity index (VEI), which runs from 1 to 8, VEI 8 being reserved for the sort of mega-eruptions that cause ice ages and mass extinctions. It ejected twenty-four cubic miles of dirt, rock, and dust into the air, about nine times as much as Krakatoa in 1883, twenty-four times as much as Mount St. Helens in 1980, and forty times as much as the eruption of Vesuvius in AD 79 that destroyed Pompeii and Herculaneum.

The tsunamis triggered by Kikai obliterated coastal towns. The eruption’s spew was enough to blanket up to 18 million square miles of land and sea. Dust and ash several feet thick smothered the fertile soil, rendering southern Japan uninhabitable for two centuries. Unable to farm, the Jomon set out for other shores in what Betty Meggers calls “the Jomon Exodus.” And that was where a second mighty phenomenon came into play.

The Kuroshio (“Black Current,” named after the dark color it lends the horizon when viewed from the shore) is the Pacific Ocean’s answer to the Atlantic’s Gulf Stream. More than twenty-two hundred years ago the Chinese called the Kuroshio by the prescient name Wei-Lu, the current to “a world in the east from which no man has ever returned.” Surging up from Taiwan, fat with warm tropic water, it arcs past Japan and Southeast Alaska and down the northwest coast. At the same time, cool, powerful offshore winds, the equivalent of Atlantic America’s Arctic blasts, race down from Siberia, pushing boats and other flotsam out into the Kuroshio.

The fleeing Jomon were driven into the Kuroshio. So were fishermen blocked from returning home by the sea-blanketing pumice. The Black Current bore them toward America—surely not the first and far from the last unwitting emissaries to make that journey.

Europeans call drifting ships “derelicts” once their crews have taken to the longboats. But the Japanese use the word hyôryô for a marine mishap in which a vessel, the hyôryô-sen, loses control and drifts without command. Traditionally its crew and passengers—hyôryô-min, drifting people—would stay aboard, awaiting their fate.

In half of known hyôryô cases, at least some hyôryô-min survived to reach land. And some of those survivors dramatically affected the societies they beached upon. Around 1260 CE, a junk drifted nearly to North America, until the California Current caught it and sent it into the westbound trade winds, which deposited it near Wailuku, Maui. Six centuries later the oral history of the event had passed down to King David Kalakaua, Hawaii’s last reigning monarch. As the tale came down, Wakalana, the reigning chief of Maui’s windward side, rescued the five hyôryô-min still alive on the junk, three men and two women. One, the captain, escaped the wreck wearing his sword; hence the incident has come to be known as the tale of the iron knife. The five castaways were treated like royalty; one of the women married Wakalana himself and launched extensive family lines on Maui and Oahu.

That was just the first accidental Japanese mission to Hawaii. By 1650, according to John Stokes, curator of Honolulu’s Bishop Museum, four more vessels had washed up, “their crews marrying into the Hawaiian aristocracy, leaving their imprint on the cultural development of the islands…. Hawaiian native culture, while basically Polynesian, included many features not found elsewhere in Polynesia.”

The Japanese presence in Hawaii may go back much further. Hawaiian legend recounts that the first Polynesian settlers there encountered diminutive menehune (“little people”), marvelous craftsmen who still dwell in deep forests and secret valleys. At that time, the Japanese were more than a foot shorter than average Polynesians and adept at many strange technologies—from firing pottery and spinning silk to forging metal—that might indeed have seemed like marvels.

Japanese influence likewise spread in mainland North America. Archaeological digs occasionally unearth traces: iron (which native Americans did not smelt) discovered in a village buried by an ancient mudslide near Lake Ozette, Washington; arrowheads hewn from Asian pottery discovered on Oregon’s coast; and, of course, the six-thousand-year-old Japanese pottery shards in Ecuador. Just as Betty Meggers found unique artifacts, viruses, and DNA markers in Ecuadoran subjects, the anthropologist Nancy Yaw Davis found telltale Japanese traits in the Zuni of northern New Mexico, distinct from all the other Pueblo peoples. Davis concluded that Japanese had landed in California in the fourteenth century, trekked inland, and helped found the Zuni Nation.

All told, the University of Washington anthropologist George Quimby estimated, between 500 and 1750 CE some 187 junks drifted from Japan to the Americas. The number of drifts increased dramatically after 1603—thanks, ironically, to the efforts of a xenophobic regime to keep foreign influences out of Japan and the Japanese in. In that year the Togugawa shogun, who had united the nation after years of civil war, closed Japan to the outside world, exempting only restricted trade through the port of Nagasaki. Western ships and castaways were to be repelled. Missionaries and other foreigners who entered were to be killed—as were Japanese who left and tried to return.

To ensure that Japanese mariners remained in coastal waters, the shoguns dictated that their boats have large rudders, designed to snap in high seas. Vessels blown offshore were helpless; to avoid capsizing, crews would cut down their main masts and drift, rudderless and unrigged, across the ocean.

Politics conspired with geography, weather, and ocean currents to set this slow-motion, accidental armada adrift. Over the centuries, the shoguns transferred their power to Edo, now Tokyo, and demanded annual tributes of rice and other goods. But Japan’s mountainous terrain made land transport impossible, so each fall and winter, after the harvest, tribute-laden vessels sailed from Osaka and other cities in the populous south up the outer coast to Edo. To get there, they had to traverse an exposed deepwater reach called Enshu-nada, the infamous Bay of Bad water. And they had to cross just when the storms blew down from Siberia—the same weather pattern that rakes Labrador, Newfoundland, and New England and drives kayaks across the Atlantic. Of ninety drifting vessels documented by the Japanese expert Arakawa Hidetoshi, storms blew 68 percent out into the Black Current during the four months from October to January.

To see where the hyôryô-min drifted, the girls of the Natural Science Club in Choshi, Japan, threw 750 bottles into the Kuroshio in October 1984 and 1985. By 1998, beachcombers had recovered 49: 7 along North America, 9 in the Hawaiian Islands, 13 in the Philippines, and 16 in the vicinity of Japan—percentages remarkably similar to those of the known hyôryô. A few swung back onto the Russian peninsula of Kamchatka, just north of Japan. Kamchatkans adopted the slang term dembei for bobbing castaways, after a Japanese fisherman named Dembei whose junk drifted there in 1697—the first known contact between Japanese and Russians.

A few twentieth-century adventurers have traveled as far in open boats as the hyôryô. In 1991, Gerard d’Aboville rowed a twenty-six-foot boat solo for 134 days and 6,200 miles, from Japan to North America. In 1970, Vital Alsar and four companions sailed a balsa raft from Ecuador to Australia, covering nearly eighty-six hundred miles in six months. And in 1952, Dr. Alain Bombard set out to prove that humans could survive being lost at sea by drifting for sixty-five days across the Atlantic in a collapsible raft, catching fish and sipping seawater. But none of these daredevils came near to lasting as long at sea as the hyôryô-min, who often drifted more than 400 and once more than 540 days. Typically just three out of a dozen in a crew would survive—the fittest and most resourceful, who were best equipped to influence, even dominate, the societies they encountered.

As the centuries progressed, the number of Japanese coastal vessels, hence the number of drifters, soared. By the mid-1800s an average of two Japanese derelicts appeared each year along the shipping lanes from California to Hawaii. Four showed up near Hawaii in one thirty-year period in the early nineteenth century; at least five crewmen survived. Many other junks passed unseen along less-traveled routes. During my visits to Sitka, I was afforded the privilege of interviewing many Tlingit elders. I would tell them one sea story, and they would reciprocate with an ancient tale of their own. One elder, Fred Hope, told me that every village along the West Coast has passed down a tale of a Japanese vessel drifting ashore nearby. To the south, around the storm-wracked mouth of the Columbia River, strandings were so frequent that the Chinook Indians developed a special word, tlohon-nipts, “those who drift ashore,” for the new arrivals.

Then, in 1854, a very different landing took place on the other side of the ocean. Commodore Matthew Perry and his “black ships” arrived to open Japan to the world. Perry found skilled interpreters—Japanese who had never left Japan but were fluent in English—waiting to meet him. How could this be in the hermetically sealed hermit shogunate?

The answer lies in the drifts along the Kuroshio. In October 1813, the junk Tokujo Maru left Tokyo, returning to Toba after delivering the shogun’s annual tribute. The nor’westers swept it out to sea and it drifted for 530 days, passing within a mile of California when offshore winds blew it out to sea. Eleven of the fourteen men aboard perished. Then, 470 miles off Mexico, an American brig hailed the hulk and rescued the three survivors. After four years away, the Tokujo Maru’s captain, Jukichi, returned to Japan. Somehow he escaped execution and secretly recorded his travels in A Captain’s Diary. Though it was officially banned, Jukichi’s Diary intrigued and influenced Japanese scholars, paving the way for Commodore Perry and for another foreign guest who arrived six years before him. “Unquestionably,” James W. Borden, the U.S. Commissioner to Hawaii, remarked in 1860, “the kindness which had been extended to shipwrecked Japanese seamen was among the most powerful reasons which finally led to the opening of that country to foreigners and foreign commerce.”