The Submerged Enigma of Yonaguni: Japan’s ‘Atlantis’ Continues to Fascinate Experts

About 25 meters beneath the crystal-clear waters surrounding Japan’s Yonaguni Island lies a breathtaking formation that has puzzled scientists, divers, and curious minds around the world for decades. This massive sandstone structure — roughly 100 meters long, 40 meters wide, and 25 meters high — features perfectly aligned steps, sharp angles, and flat surfaces that appear to have been carved with precision.

The discovery was made in 1986 by diving instructor Kihachiro Aratake during an exploration near the island, located about 100 kilometers from Taiwan. In search of new dive spots for tourists, Aratake was stunned when he came across what looked like ancient underwater architecture. He immediately alerted researchers at the University of the Ryukyus, launching what would soon become known as the “Japanese Atlantis” — a nod to the legendary lost city described by Plato.

Since then, the scientific community has debated whether the site is a remarkable natural rock formation or the remains of an ancient, unknown civilization.

One of the strongest advocates of the human-made theory is geophysicist Masaaki Kimura, professor emeritus at the University of the Ryukyus. After more than two decades of studying the site, Kimura believes the structures could have been built over 10,000 years ago by early inhabitants of the region, during a time when sea levels were significantly lower. He later revised the estimate to between 2,000 and 3,000 years old.

Kimura points to what he claims are carvings in the stone that resemble animals and symbols. In an interview with National Geographic, he described a formation he believes looks like an underwater sphinx, with features similar to ancient Chinese or Okinawan kings.

He also cites the region’s intense seismic activity as supporting evidence. In 1771, a massive tsunami with waves reaching up to 40 meters devastated Yonaguni, killing an estimated 12,000 people. According to Kimura, it’s not unreasonable to think that a similar event could have submerged an entire city.

Despite the ongoing debate, the mystery of Yonaguni’s underwater structures continues to captivate the imagination of explorers and researchers alike, making it one of the most intriguing dive sites on the planet.

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