How a Stone Tool Canoe Recreated a 30,000-Year-Old Voyage from Taiwan to Japan

Five Paddlers, 225 Kilometers and a Powerful Ocean Current

In July 2019, five experienced paddlers left the east coast of Taiwan in a wooden canoe made with replicas of Paleolithic stone tools. Their destination was Yonaguni, Japan's westernmost Ryukyu island, 225 kilometers away along their planned voyage. Between them and land lay the Kuroshio, one of the world's strongest ocean currents.

The crew, four men and one woman, paddled for more than 45 hours in a canoe named Sugime. They navigated using the sun, stars and ocean swells, without maps, compasses or GPS. Two escort boats accompanied them for safety, while the paddlers relied on methods intended to reflect those available to people about 30,000 years ago.

Their successful arrival addressed a question that has occupied archaeologists and anthropologists for decades: how could people with stone tools, no metal and no maps have crossed the sea from Taiwan to the Ryukyu Islands during the Paleolithic, or Old Stone Age?

A research team led by Professor Yousuke Kaifu of the University of Tokyo combined boat construction, experimental voyages and computer simulations to investigate that journey. Their work points to a demanding combination of practical boatbuilding, endurance, teamwork and deliberate navigation.

The experiment also helps explain why simply floating out to sea would have been an unreliable way to reach the islands. The same current that modern paddlers struggled to cross tends to carry drifting objects away from the Ryukyus. Early settlers would have needed to work with an ocean they could observe but could not map as researchers can today.

What the Islands Reveal About Early Arrivals

The Ryukyu Islands stretch for more than 1,200 kilometers between Kyushu in southern Japan and Taiwan. Archaeological discoveries across the chain include human remains, stone tools, shell beads and the world's oldest fishhooks. These finds date from about 35,000 to 27,500 years ago.

The evidence suggests that Homo sapiens reached the islands during the late Paleolithic from two directions: southward from Kyushu and northward from Taiwan. The southern approach involved a particularly difficult stretch of open water.

The strait between Taiwan and Yonaguni is more than 100 kilometers wide. The Kuroshio flows through this region at speeds of 1 to 2 meters per second, strong enough to push a slow vessel away from its intended course even while its occupants are paddling.

Visibility adds another problem. The islands are low and often cannot be seen from the opposite shore. Yonaguni is invisible from Taiwan's coast, although it can appear above the horizon when viewed from the high mountains of northern Taiwan.

For an ancient crew, that meant spending much of the crossing without a destination in sight. The archaeological evidence places people on the islands, but wooden boats rarely survive for thousands of years. Researchers therefore turned to reconstruction and testing to investigate how those arrivals might have happened.

From Raft Experiments to a Cedar Canoe

Kaifu's project began in 2013. Its approach drew inspiration from the 1947 Kon-Tiki expedition, when Norwegian explorer Thor Heyerdahl sailed a balsa wood raft across the Pacific to test ideas about ancient migration. Kaifu's team could also draw on decades of archaeological research and modern scientific tools.

The researchers initially tried rafts made from reed bundles and bamboo. Both materials were plausible choices because they occurred among the region's plants. On the water, however, these craft proved too slow and fragile for the crossing. They either failed to make headway against the current or broke apart in the open sea.

The failures prompted the team to try a dugout canoe, a boat made by hollowing out a tree trunk. Using replicas of stone axes and adzes modeled on tools from Paleolithic sites in Japan, they felled a Japanese cedar tree about one meter thick.

The builders then hollowed and shaped the trunk into Sugime, a canoe 7.5 meters long. The work required thousands of blows with stone tools and careful shaping to produce a vessel capable of traveling at sea.

Fire and stones were used to polish the canoe, echoing techniques seen in dugouts from the later Jōmon period. Construction was itself part of the experiment: a successful crossing required a boat that could be made with the tools being tested, as well as one that could survive the water.

More Than 45 Hours at Sea

Sugime's July 2019 voyage placed the reconstructed canoe in the conditions the project was trying to understand. Its five paddlers had experience, but they still faced prolonged exertion, uncertain visibility and a current that demanded repeated changes of heading.

The Kuroshio battered the canoe as the crew worked to hold their course. They had to bail out water while continuing to paddle. Fatigue forced them to take turns resting, and the canoe drifted during those pauses.

Clouds sometimes obscured the stars. When that happened, the movement of ocean swells and the position of the sun became the crew's remaining directional clues. For long stretches, they could not see Yonaguni.

After more than 45 hours, Sugime reached the island. The voyage demonstrated that a canoe constructed with Paleolithic technology could complete the crossing when handled by paddlers with the necessary strength, skill and navigational knowledge.

The project's main stages unfolded over several years:

• 2013: Kaifu's project began, eventually testing reed and bamboo rafts before turning to a dugout canoe.
• July 2019: Five paddlers took Sugime from eastern Taiwan to Yonaguni on a voyage of 225 kilometers lasting more than 45 hours.
• By June 30, 2025: The successful crossing and computer simulations together supported an explanation based on purposeful navigation and careful preparation.

Reconstructing an Ocean from 30,000 Years Ago

The 2019 voyage took place in modern waters. To investigate the crossing under Paleolithic conditions, researchers used a supercomputer to simulate hundreds of virtual journeys, accounting for changes in sea level, current speed and climate.

The simulations indicated that the Kuroshio was likely 10 to 20 percent faster during the last glacial period than it is today. Ancient travelers may therefore have faced a stronger current than the crew of Sugime encountered.

The models also identified a strategy that improved the chances of reaching the islands: launch from northern Taiwan and paddle at a slight angle against the current, rather than point directly toward the destination.

A boat's direction through the water and its actual path across the sea can differ because a current pushes it sideways. Angling against that push helps compensate for the movement of the water. For Paleolithic paddlers, choosing such a heading would have required close observation and planning.

Yu-Lin Chang, a physical oceanographer and co-author of the study, described how the simulations changed her expectations:

The Kuroshio Current is generally considered dangerous to navigate. I thought if you entered it, you could only drift aimlessly. But the results of our simulations went far beyond what I had imagined. I'm pleased this work helped illuminate how ocean voyages may have occurred 30,000 years ago.

The computer results and the physical crossing reinforce the same explanation: the journey was achievable, even in a stronger current, when paddlers chose their departure area and direction carefully.

Why the Failed Rafts Matter

The reed and bamboo trials helped narrow the practical choices available for this route. Materials that could be assembled into a floating platform did not necessarily produce a vessel fast or durable enough to cross the Kuroshio.

The tested rafts struggled because the current was too strong and their performance too limited. The dugout canoe supplied the greater speed and durability needed to complete the journey.

Rafts may have served people in other regions, but this project found them inadequate for the Taiwan to Yonaguni crossing. The successful canoe connected the problem of migration to another problem: whether people could make a suitable boat using the tools available to them.

Edge-ground stone axes found in both Japan and Australia suggest that technology capable of supporting dugout construction was widespread in the Western Pacific by this period. These tools had sharpened edges produced through grinding, giving builders a means of working substantial pieces of wood.

The absence of surviving Paleolithic boats leaves the exact craft used by the original travelers unknown. Sugime provides a tested example of how stone tools could turn a tree into a vessel capable of making the journey.

The experiment also made the human requirements apparent. Every member of a crew, regardless of gender, needed to be a competent paddler. Effective leadership mattered because heading, effort, rest and the handling of water inside the boat all had to be managed during a long crossing.

Finding Land Without Maps or GPS

The crew's navigation depended on reading natural signs. The sun and stars offered direction, ocean swells provided further clues, and bird behavior formed part of the environmental knowledge considered in understanding how early seafarers could find their way.

Yonaguni's visibility from high mountains in northern Taiwan raises the possibility that ancient travelers scouted a destination from elevated ground before setting out. Once at sea, they would have needed to maintain their course through long periods when land disappeared below the horizon.

Researchers also tested the possibility of accidental arrival by releasing 138 buoys equipped with satellite tracking from Taiwan. Only four came within 20 kilometers of the Ryukyu Islands, and those approaches were driven by storms.

The result helps explain the importance of active paddling. Drifting with the Kuroshio generally takes an object away from the islands. A crew trying to reach them needed to choose and maintain a course instead of relying on the current to deliver the boat.

Kaifu described the early travelers as skilled people whose success depended on shared purpose:

Those male and female pioneers must have all been experienced paddlers with effective strategies and a strong will to explore the unknown.

The navigation problem brings the project's different findings together. A seaworthy boat, a suitable departure point and sustained paddling all mattered because the island could remain out of sight while the water pushed the crew away from it.

Why Going Back Could Have Been Harder

The successful crossing concerned travel from Taiwan toward Yonaguni. Researchers believe a return journey would have been much more difficult, and perhaps impossible, for Paleolithic travelers.

Without maps or knowledge of the Kuroshio's flow patterns, early navigators would have struggled to plan a route home. Their migration was therefore likely a journey in one direction, with settlers leaving their homeland permanently.

The experience echoes other ancient seafaring traditions, including Polynesian voyages across vast stretches of the Pacific using environmental cues. The Ryukyu crossing stands among the earliest and most challenging examples of maritime migration.

For the people in the canoe, the demands extended beyond surviving a difficult passage. A successful arrival could mean beginning life in a place from which returning was beyond their practical reach.

What the Voyage Changes About Early Seafaring

Sugime's crossing challenges portrayals of Paleolithic people as primitive. Building the canoe required technical skill and sustained labor. Reaching Yonaguni required planning, cooperation, the ability to interpret the sea and a willingness to take risks.

Peter Bellwood, an archaeologist at the Australian National University, placed the crossing in the wider history of human migration:

Such a crossing between islands would have been one of the oldest, and among the longest, in the history of Homo sapiens up to that period, exceeded only by the migration to Australia from eastern Indonesia some 50,000 years ago.

The ability to build boats, plan complicated journeys and navigate open water was a key part of the spread of Homo sapiens around the world. The Ryukyu project gives those abilities a concrete form: stone tools shaping cedar, five paddlers sharing the work and a canoe maintaining a course through a powerful current.

Experimental archaeology uses reconstruction and practical tests to investigate questions that artifacts alone cannot answer. In this case, the failed rafts were informative alongside the successful canoe, while computer simulations tested how the proposed journey would work in an earlier ocean.

Kaifu's explanation of the project's value rests on a basic difficulty: the sea washes away much of the physical evidence. Recreating the voyage gives researchers another way to investigate the challenges early travelers faced and the skills that could have brought them to the islands.

Key Points

• Ryukyu archaeological finds dating from about 35,000 to 27,500 years ago indicate arrivals from Kyushu and Taiwan.
• In July 2019, four men and one woman paddled the 7.5-meter canoe Sugime from eastern Taiwan to Yonaguni, completing a voyage of 225 kilometers in more than 45 hours.
• The canoe was made from Japanese cedar using replicas of Paleolithic stone tools. Earlier reed and bamboo rafts failed.
• Computer simulations suggest the ancient Kuroshio was 10 to 20 percent faster, but a departure from northern Taiwan and a heading angled against the current improved the chances of success.
• Only four of 138 tracking buoys came within 20 kilometers of the Ryukyus, supporting an explanation based on intentional navigation.
• Researchers consider the ancient migration likely to have been a journey without a return, requiring skilled paddlers, teamwork and careful preparation.