The Yonaguni Monument: Is it the Lost City of Atlantis?

In the early 1980s, a young Japanese diver discovered the Yonaguni Monument. Could it be the lost city of Atlantis?

In the early 1980s, a young diver named Kihachiro Aratake was scouting for dive sites on the remote Japanese island of Yonaguni. That’s when he discovered something underwater that took his breath away. He described it as an “underwater Machu Picchu.” But, is the now-called Yonaguni Monument in fact closer to the lost city of Atlantis?

Diving the Yonaguni Monument

I’m listening to Aratake’s story 30 years on, and as he reaches this part of his tale, his eyes widen in excitement. The magic lives on, and so does the mystery.

Is it an ancient monument, the remains of a legendary city like Atlantis, swallowed by the ocean thousands of years ago? Did aliens build it? Or is it a natural rock formation? Archaeologists and geologists are still at loggerheads 30 years after Aratake discovered it.

So naturally, it’s the first thing I want to see when I arrive here for a dive holiday. Aratake tells me I must decide for myself. I’m diving with Sou-Wes Diving, run by Aratake’s son, Shorty, and he sizes us up carefully before taking us to the dive site. He tests our skills first at another site before deciding whether we’re up for it and decides that we are.

The Monument is located close to shore and while it’s a shallow dive, between 15 to 40 feet (4.5 to 12 m), the area is sometimes subject to strong currents.

You’ll enter the site through a small tunnel that opens on to a flat, square area. As you emerge from the tunnel,  you’ll see two massive columns right in front of you. These have perfectly square edges, stretching up to the water’s surface. From here you follow a flat road around the tall walls of the monument to an area that looks like a stage.

Large steps lead up to the stage, with more steps leading on to higher levels of the structure. At the edge of the stage, the walls drop down steeply to a depth of around 14 m. You can just imagine crowds standing below, looking up at some kind of spectacle.

On our dive, the water is incredibly clear, with visibility of at least 120 feet (37 m). I peer over the side of the monument into the gully, where I can see two turtles gliding along, far below us.

Past the stage there is a deep, triangular alcove, which Aratake believes was a chapel or altar. Shorty points out that it faces exactly due north, and a large slab of rock sits just before the apex, almost like a sacrificial platform.

A little further along is another perfectly symmetrical structure, which looks like a giant turtle. Could this have been a god-like creature that the ancients worshipped?

So, what is the Yonaguni Monument?

I must admit: it’s pretty convincing. The straight edges of the steps and stage are at perfect 90-degree angles — how could these have formed naturally? Geologists argue that the rock formations are sedimentary, made of sandstone. Some archaeologists claim that the monument was carved out of stone (sandstone is relatively easy to carve, isn’t it?). But if this monument was built on land and then swallowed by the sea, it must have happened over 10,000 years ago, the last time sea levels rose. This means it predates the Egyptian pyramids and megalithic structures such as Stonehenge by about 5,000 years.

Other Yonaguni dive sites

Whether you believe this is a manmade structure or a natural-rock formation, it’s still an incredible sight. And it’s not the only amazing dive site in Yonaguni.

Divers have surveyed 67 sites here. Many feature beautiful caverns and caves, pristine coral reefs and other striking features, such as large fields of anemones and enormous gorgonian fans. And better still, even in November the water temperature is 84 F (29 C), thanks to a warm current that runs up the east coast of Taiwan. There’s plenty of marine life here too, everything from brightly colored anemonefish, to turtles, rays and, in season, huge schools of hammerhead sharks.

So, is the Yonaguni Monument manmade? As Aratake says, you must decide for yourself. Its mystique has lasted over 30 years so far, no doubt it will last many more.

Getting There: ANA has daily connecting flights to Naha, Okinawa from Tokyo, but as Naha is an international airport, you can also fly there directly from Taipei, Seoul, Shanghai and Hong Kong. Yonaguni Island is another 1.5 hours’ flight from Naha, traveling with domestic airline Ryuku Air Commuter.

Where to Stay: The island has several bed-and-breakfast-style accommodations. Sou-Wes Diving owns and operates Hotel Irifune. The hotel offers Western- or Japanese-style rooms, and all meals are included.

Deborah Dickson-Smith is one half of Diveplanit. She manages the dive-travel website  her partner Simon Mallender, based in Australia.