A crew of scientists and volunteers paddled a handmade dugout canoe over 140 miles (225 kilometers) from eastern Taiwan to Yonaguni Island, Japan, navigating the powerful Kuroshio Current — a major oceanic flow akin to the Gulf Stream. The journey took more than 45 hours, and aimed to replicate what may have been a key migratory route for early humans some 30,000 years ago.

A dugout canoe is pictured before departure on a crossing across a region of the East China Sea to Yonaguni Island, with leaf wave guards at the bow and stern, near Ushibi, Taiwan, in this handout image released on June 25, 2025. Yousuke Kaifu/Handout via REUTERS THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. NO RESALES. NO ARCHIVES

Reconstructing Ancient Maritime Technology

According to Reuters, the voyage was part of a project led by anthropologist Yousuke Kaifu of the University of Tokyo and documented in the journal Science Advances. The team built a 25-foot-long (7.5-meter) canoe called Sugime using only replicas of Paleolithic stone tools such as axes and adzes. The canoe was carved from a Japanese cedar tree, echoing the rudimentary construction methods of our distant ancestors.

Unlike modern navigation techniques, the crew relied on sunlight, stars, and ocean swells to steer their way. Though accompanied by two safety escort boats, the core team — four men and one woman — experienced extreme fatigue and weathered open-sea conditions while drifting for several hours to recover.

A Journey Rooted in Prehistoric Evidence

This experimental voyage was designed to test a long-standing question in human history: how did early humans reach remote Pacific islands without maps, metal tools, or modern ships? Archaeological data suggest that by around 30,000 years ago, early humans had crossed from Taiwan to the Ryukyu island chain, which includes Yonaguni and Okinawa. But the sheer difficulty of such journeys — especially across the Kuroshio Current, one of the most intense in the world — left researchers questioning how they managed it.

An axe accurate to a period of 30,000 years ago, that scientists used to make a dugout canoe for a crossing across a region of the East China Sea from Taiwan near Ushibi to Yonaguni Island, traversing the Kuroshio current, is seen at Noto Peninsula, Japan, in this handout image released on June 25, 2025. Yousuke Kaifu/Handout via REUTERS THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. NO RESALES. NO ARCHIVES

Initial attempts to recreate such journeys using reed and bamboo rafts had failed. These materials proved too slow and unstable to overcome the powerful current, forcing researchers to reconsider which type of vessel ancient people might have used.

“We found that Paleolithic people could cross the sea with the strong ocean current if they had dugout canoes and were skillful, experienced paddlers and navigators,” Kaifu said. “They had to face the risk of being drifted… and the possibility that they would never be able to come back to their homeland.”

New Models Confirm Ancient Feasibility

In a companion study also published in Science Advances, researchers used paleo-ocean modeling to simulate sea conditions between Taiwan and Yonaguni during the Paleolithic period. According to Yu-Lin Chang, a physical oceanographer at the Japan Agency for Marine-Earth Science and Technology, these models confirmed that crossing the sea 30,000 years ago was scientifically possible, even when the Kuroshio was stronger than it is today.

“However, ocean conditions were highly variable,” Chang noted. “Thus, ancient people may have encountered unpredictable weather conditions during their journey, which could have led to failure.”

A dugout canoe with four men and one woman paddling is pictured during a crossing across a region of the East China Sea from near Ushibi, Taiwan to Yonaguni Island, traversing the Kuroshio current, in this handout image released on June 25, 2025. Yousuke Kaifu/Handout via REUTERS THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. NO RESALES. NO ARCHIVES

In the Spirit of Kon-Tiki

This effort echoes the legendary Kon-Tiki expedition of 1947, when Norwegian explorer Thor Heyerdahl sailed a raft across the Pacific to test theories of prehistoric migration from South America to Polynesia. Though Heyerdahl’s migration theory has since been debunked, Kaifu acknowledged his voyage as a valuable early attempt at experimental archaeology.

“Compared to the time of the Kon-Tiki, we now have more archaeological and other evidence to build realistic models,” Kaifu said, emphasizing how modern science can shed new light on ancient ingenuity.

“Through the project with many failures, we have learned the difficulties of crossing the ocean, and this experience gave us a deep respect for our Paleolithic ancestors,” Kaifu concluded.