Is the 10,000-Year-Old Yonaguni Monument a Man-Made Marvel or Nature's Art?

The enigmatic underwater Yonaguni monument. Source: nudiblue/Adobe Stock 

Nestled along the southern coast of Yonaguni, Japan, are enigmatic submerged ruins that have captured the fascination of researchers and ignited fervent debates. Believed to date back approximately 10,000 years, the origin of the Yonaguni monument remains shrouded in mystery. Hotly debated among experts, some asserting that these formations are unmistakably man-made, while others, adopting a more conservative stance, attribute their creation to the forces of natural phenomena. This intriguing archaeological site continues to be a subject of exploration, sparking curiosity and speculation about its true origins. 

Discovery of the Yonaguni Monument And Initial Controversy 

The unique and awe-inspiring site was discovered in 1995 by a diver who strayed too far off the Okinawa shore and was dumb-struck when he stumbled upon the sunken arrangement of monolithic blocks "as if terraced into the side of a mountain".  The structure sparked instant controversy and attracted crowds of diving archaeologists, media and curious hobbyists, none of whom were able to ascertain its identity. 

Late in the following year, more serious attempts were made to gather data and map out the structure. The process revealed many surprising findings including what appears to be a massive arch or gateway of huge stone blocks which appeared to fit together perfectly, right angled joins, carvings and what appeared to be stairways, paved streets and crossroads and grand staircases leading to plazas surrounded by pairs of towering features resembling pylons.  

Divers investigate the huge rock structure at Yonaguni, Okinawa. (nudiblue/ Adobe Stock) 

As teams of expert divers fanned out from the south coast of Okinawa using grid-search patterns, they found five sub surface archaeological sites near three offshore islands. The locations vary at depths from 100 (30.5 m) to only 20 feet (6 m). 

Proponents of the view that the sites are man-made point out features such as two round holes (about 2 feet wide, 61 cm) and a straight row of smaller holes that appear to have been an attempt to split off a section of the rock by means of wedges, as in ancient quarries. Professor Masaaki Kimura, a marine seismologist of the University of the Rykyus, also pointed out a number of marks, such as a plus sign and a V shape, that appear to show that human beings worked the stone and could have been made by wedge-like tools called kusabi. 

This is a model of Yonaguni Monument, the concrete phenomenon found under the sea off Yonaguni Island, Japan.(Liangtai Lin) 

While many of the features seen at Yonaguni are also seen in natural sandstone formations throughout the world, the concentration of so many peculiar formations and 90-degree angles in such a small area seems peculiar. 

Natural Formations 

Despite the unusual features displayed at Yonaguni, there remains a small group of scientists who have studied the formation and who are adamant that the large blocks formed naturally as a result of tectonic movement and other natural phenomena. 

Underwater view of the massive Yonaguni Monument. (Vincent Lou/CC BY 2.0) 

Geologist Robert Schoch of Boston University is one scientists who believes that the structures were naturally formed and acknowledges that they may have been used or modified by humans in the past. He points to the fact that the site lies in an earthquake-prone region and that earthquakes tend to fracture rocks in a regular manner.  This is also the view of John Anthony West who believes that the so-called walls are simply natural horizontal 'platforms' which fell into a vertical position when rock below them eroded and the alleged roads are simply channels in the rock. 

Other examples of natural formations with flat faces and sharp, straight edges are the basalt columns of the Giant's Causeway and the natural staircase formation on Old Rag Mountain. 

Remnants of an Ancient Civilization? 

Nevertheless, many scientists are persisting in their search for further evidence of their man-made nature with the belief that the stone structures are the remnants of an old city that must have existed around 10,000 years ago when the sea level was much lower than it is today since it does not appear that the site ‘fell’ into the sea. 

One proponent of this view is explorer and researcher Graham Hancock who in his book titled  Underworld writes: “It was the submerged structures of Japan that first awakened me to the possibility that an underworld in history, unrecognized by archaeologists, could lie concealed and forgotten beneath the sea” (Hancock 2002). 

Hancock draws parallels between Yonaguni and other ruins found beneath the waters of Lake Titicaca and in Dwarka, off the coast of India, which offer further evidence for the existence of a vast underwater world containing structures stretching back to the dimmest chapters of human antiquity. 

If the structures at Yonaguni are indeed the remains of an ancient city, one possibility is the prehistoric inhabitants of Japan called the Jomon, who existed from about 12,000 BC to around 300 BC and who developed a sophisticated culture. The Jomon is often compared to pre-Columbian cultures of Pacific Northwest North America because in both regions cultural complexity developed within a primarily hunting-gathering context. 

Early stage of Jomon pottery. (Public Domain) 

Although their society was considered ‘primitive’ by the standards of later times, they were the first culture on Earth to develop pottery, according to mainstream theorists. Examples of this technology date back to the time when many of the submerged structures of Yonaguni would have been above water, and if they were in fact built by human hands, this would have been the time that their construction was underway. 

Researchers are continuing to investigate these unique and perplexing underwater worlds with regards to how they relate to our ancient past and to unravel the mysteries surrounding their true origins. 

Certainly, the investigation into the Yonaguni Monument remains a continuous process, and we eagerly anticipate the day when the mystery is ultimately unraveled. Employing cutting-edge technologies such as underwater sonar mapping, 3D modeling, and geophysical studies, researchers strive to unveil the origins of this enigmatic site. Patiently, we observe the ongoing efforts with anticipation. 

By Joanna Gillan