Popular Mechanics 42.9%
A Scientist Says a Baffling Seafloor Structure Marks Japan’s Atlantis
By Darren Orf - 7/8/2026, 12:30 PM - 611 words
Faulty reasoning signals
- Confirmation Bias - 14.4% (88 hits)
- Anchoring Bias - 5.1% (31 hits)
- Availability Heuristic - 14.2% (87 hits)
- Representativeness Heuristic - 17.3% (106 hits)
- Hindsight Bias - 8.7% (53 hits)
- Overconfidence Bias - 6.1% (37 hits)
- Framing Effect - 8.7% (53 hits)
- Loss Aversion - 0%
- Status Quo Bias - 4.1% (25 hits)
- Sunk Cost Effect - 0%
- Optimism Bias - 3.8% (23 hits)
- Pessimism Bias - 0%
Article text
A Scientist Says a Baffling Seafloor Structure Marks Japan’s Atlantis
In 1986, while searching for new hammerhead shark viewing points off the coast of Yonaguni Island—the westernmost Japanese island, 70 miles east of Taiwan—diving tour guide Kihachiro Aratake stumbled across an inexplainable underwater formation.
The rocky seafloor structure consists of rocks shaped at nearly perfect 90-degree angles, resembling terraces leading to an ancient, man-made structure lost in the inhospitable waters of the East China and Philippine seas.
“When I first found it […] my hair stood on end.
I had goosebumps all over.
It was overwhelming,” Aratake told the BBC some 35 years after the discovery.
“Upon discovering it, I realized that this would become a treasure of Yonaguni Island.”
As it turned out, these mysterious step-like rocks would become much more than that.
In the following years, the Yonaguni Monument (as it was eventually called) became the center of a debate around its origin.
Was this monument the creation of some island society lost to history, or simply a beautiful-yet-natural rock formation?
One of the first scientists to study the site was Masaaki Kimura, a geologist at the University of the Ryukyus in Okinawa, Japan.
He suggested that the monument was a kind of step pyramid, possibly constructed several thousand years ago, before the sea level rise that followed the last Ice Age eventually submerged it.
Some others even suggested that the monument is a remnant of the lost city of Mu—a mythical place believed to have existed in the Pacific before disappearing beneath the waves in a story similar to the tale of Atlantis.
“I think it’s very difficult to explain away their origin as being purely natural, because of the vast amount of evidence of man’s influence on the structures,” Kimura told National Geographic in 2007.
Finding such a manmade monument, measuring 50 meters long and around 20 meters wide, would rewrite the history of the Ryukyu Island chain.
But not all scientists are convinced.
One of the skeptics is Robert Schoch, a professor of natural sciences at Boston University, who’s been the most vocal proponent of the idea that the Yonaguni Monument is natural—or at the very least, mostly natural.
“It is indeed an absolutely incredible structure, and well worth seeing, but I must conclude that, based on all of the evidence, it is primarily a natural structure,” Schoch wrote in a blog on his personal website.
Schoch has appeared in several articles—and even documentaries—to explain his findings.
“Parts may have been ‘touched up’ by ancient humans and the ancient inhabitants of the island may have both admired and utilized the Yonaguni Monument.
We can consider the famous prehistoric cave paintings of Europe.
The caves themselves are natural […] [but] paintings on their walls and ceilings are artificial productions by early humans.”
Schoch observed that the structure is made from sandstone and mudstone, which both erodes in flat planes across the surface and fractures horizontally, forming what appear to be human-made terraces.
Takayuki Ogata, a geologist at Ryukyu University, backs up these claims, saying that the underwater formations resemble those still visible on the surface.
“I was impressed by the formations underwater, which are continuous from the land above the water’s surface” Ogata told the BBC.
“I’ve researched several sites and have done a lot of fieldwork, but this was the first time I’d seen formations that were continuous from land to underwater.”
Today, neither Japan’s Agency for Cultural Affairs nor the government of Okinawa Prefecture consider the area of cultural significance.
But whether a natural phenomenon or a man-made wonder, the Yonaguni monument—just as Aratake predicted 40 years ago—remains a treasure for the small Japanese island.