The Yonaguni Enigma: The 'Japanese Atlantis' That Attracts Curious Spectators and Experts

At a depth of about 25 meters, in waters near the Ryukyu Islands, south of Japan , lies one of the most enigmatic underwater formations on the planet. These are gigantic stone structures with surprisingly straight lines and ramps that extend for 200 meters, and whose shape appears to be in the form of a pyramid.

The discovery dates back to 1986, when diving instructor Kihachiro Aratake was exploring the area off the coast of the Japanese island of Yonaguni, about 100 kilometers east of Taiwan. During the dive, he thought he could see a spiral staircase among the rock formations. He had found what is now known as the Yonaguni Monument, nicknamed by many as the "Japanese Atlantis."

Since then, there has been a constant debate about whether the structure is natural or human-made. One of the leading proponents of its artificial origin is Masaaki Kimura, professor emeritus of geophysics at the University of Ryukyu, who has researched the site for decades. Kimura argues that the formations could be the remains of an ancient city, possibly built by the Jomon people more than 10,000 years ago.

“The place immediately reminded me of the pyramids. I felt like I was in ancient Egypt,” he said in a 2017 documentary. According to his theory, marks in the rock that appear to have been made by tools, structures that resemble animals, or even what Kimura believed to be an underwater sphinx with features of an Okinawan or ancient Chinese king could be evidence of their human origin. Kimura also suggests that a tsunami like the one in 1771, which generated waves up to 40 meters high, could have submerged these structures at a time when sea levels were lower and the area was still above water.

To support this hypothesis, some have pointed to the presence of arched entrances, right angles, and symmetrical structures that are difficult to explain by purely natural processes. "I think it's very difficult to attribute all of this to erosion, given the extensive evidence of human influence on the forms," he told the BBC.

However, other experts disagree. Geologist Robert Schoch of Boston University argues that the supposedly straight lines and precise angles aren't as regular as they're said to be. "It's basic geology. Sandstone stratigraphy tends to fracture along straight planes, especially in areas with high tectonic activity," he stated in an interview with National Geographic.

Wolf Wichmann, a geologist and professional diver, agrees. According to him, elements such as wave channels, perforations made by sea urchins and shells, and natural coatings on the rock show typical patterns of marine erosion. He went on to explain that the surfaces and walls follow the natural weak zones of the sedimentary rock and the perpendicular fractures that develop over time.

Takayuki Ogata, a scientist also at the University of Ryukyu, adds that when he first saw the formations, he noticed that they resembled common landforms. What surprised him most was that they extended from the mainland to the seafloor. To him, the structure appears to be part of a larger rock mass that has gradually and naturally formed.

Meanwhile, geologist Robert Schoch of Boston University went so far as to claim that it is most likely a natural formation, modified by humans. The rocks in the area, he says, exhibit well-defined bedding planes, along with numerous parallel lines and vertical fractures, common in seismic regions like those in this area. And earthquakes tend to fracture rocks in regular ways, creating shapes that can appear artificial.

Meanwhile, the mystery of the Yonaguni monument lives on. Although the theory that it is a natural formation is gaining traction , many remain fascinated by the possibility that a little-known civilization left its mark beneath the ocean. The legend continues to attract researchers, divers, and curious people seeking new clues about its origins.