Yonaguni Monument: "Japan's Atlantis" Is A Site Of Geology, History, And Controversy

This is the Yonaguni monument, a towering underwater site that's popular with divers and ecologists for its peculiar features and incredible biodiversity. Over the years there have been plenty of ideas about what this monument is, from a giant human-made monolith to a natural ecological feature that happens to look like a pyramid. So, what is it?

What is the Yonaguni monument?

The Yonaguni monument sits near the Ryukyu Islands of Japan at a depth of 25 meters (82 feet) below sea level, making it an ideal attraction for divers looking for diverse marine life. It’s no easy dive, though, as strong currents in the area make it a tricky swim for anyone except experienced visitors. 

It was discovered in 1987 after Kihachiro Aratake went looking for a new and interesting site to take tourists to. As they approached the area, large stone formations rose in front of them, which Aratake believed to resemble human archaeological structures. Upon returning, Aratake called on scientists from the University of the Ryūkyūs to explore the area, and it was later named the Yonaguni Monument.

Since its discovery, it has garnered huge interest in how the formations got there. Nicknamed by some as Japan’s “Atlantis”, the geometric shapes and smooth rock carvings of the monument resemble an ancient underwater city, leading many to question its origins.

Japan's Atlantis or a fascinating rock?

Aratake believed that if the monument had not been carved by the sea gods themselves, it must have been created by a human civilization at some point in history. Some even claimed it was the legendary lost continent of Lemuria, a mythical continent that supposedly sunk beneath the Indian Ocean thousands of years ago. 

One of the leading scientists who first visited the site dated the rocks to around 10,000 years ago, at which point they would have been above sea level. This scientist, named Masaaki Kimura, postulated that it could in fact be Lemuria (which was also called the continent of Mu), and claimed that he could pick out cultural buildings such as pyramids, castles, and a stadium within the monument; he later reduced his estimate to around 2,000-3,000 years old instead, but remained in his belief of artificial construction.

Another prominent proponent of this view is Graham Hancock, a British author known for his controversial theories on "lost civilizations." For decades, he has written and spoken about Yonaguni, arguing that the site features human-made terraces, steps, megaliths, arches, and what appears to be a carved rock “face.” He even presented these ideas on the Joe Rogan Experience podcast during his now-infamous debate with archaeologist Flint Dibble.

Many scientists have dismissed claims that Yonaguni was built by human hands, labeling them as pseudoarchaeology. In an article called “An Enigmatic Ancient Underwater Structure off the Coast of Yonaguni Island, Japan”, Dr Robert Schoch, who holds a PhD in geology and geophysics, made the case that the monument is natural, noting a number of consistent features with nearby geological structures. It's located in an earthquake-prone region, and the fractures and flat faces that make up the stepped shape are typical of other sandstone formations.

It’s also possible that volcanic and geological forces can produce strange, angular formations like this. Known as columnar jointing, it’s a phenomenon seen in the natural world across the planet, from the coast of Scotland to Devils Tower in Wyoming.

This explanation was later built on by a number of experts in the field, due to both the appearance of the overall monument – when looking at the larger picture, it looks a lot more like a bizarre rock than an ancient city – and the timings when any possible ancient civilizations could have built it, if it was at all viable. 

Essentially, if the Yonaguni Monument were artificial, it would have to have been built before rising sea levels submerged it, which is at least 12,000 years ago. This would place its construction earlier than any known sophisticated civilization, including the Göbekli Tepe. The prevailing consensus is that the ability to construct large, complex sites typically emerges after the development of agriculture (around 12,000 years ago), which enables food surpluses, centralized power structures, and the specialization of skills.

If the Yonaguni Monument were ever proven to be human-made, it would suggest the existence of a highly advanced, previously unknown civilization that predated all others. Accepting this theory would require a total reworking of human history.

In other words, it’s probably just a big rock, which is much less fun to think about.