Reporter: Mark Simkin
North Asia correspondent Mark Simkin and cameraman Jun Matsuzono donned wetsuits and diving gear to bring back this story from underneath the waters off Yonaguni, a tiny dot in the island chain known as Okinawa.
At the very end of the Japanese archipelago, Yonaguni is the site of mysterious underwater carvings believed by locals to be the remnants of a vast underwater city, a kind of Japanese Atlantis. ďItís extraordinary,Ē says Simkin.
ďAbsolutely enormous, and very beautiful, though the key question is whether the currents somehow carved the rocks.Ē The ruins, if thatís what they are, stretch for kilometres, but the centrepiece is a 300-metre long monument shaped a bit like a giant pyramid. However, nothing is known about who Ė or what Ė made it. An intriguing mystery.
SIMKIN: At the end of the Japanese archipelago lies Yonaguni, shrouded in mist and mystery. The adults sing of their islandís beauty while the children are told legends of its past Ė stories about a mysterious castle underneath the sea.
JAPANESE SINGING: A long time ago, a man called Taro Urashima was taken to the Sea Godís palace by a turtle he had rescued. The beauty of the underwater palace could not be described, even in heaven.
SIMKIN: Itís an image that has a special place in Okinawan legend. For centuries, stories about underwater cities have appeared in song and story passed down from generation to generation.
JAPANESE WOMAN: Our grandfathers often said that the sea surrounding Yonaguni Island was very deep. When I was at primary school and first heard the stories of the Sea Godís palace and Taro Urashima, I used to wonder if there was a Sea Godís palace close to Yonaguni Island.
SIMKIN: Such thoughts have long been dismissed as fantasy but what if fiction was based on fact? Scientists are now investigating a remarkable but virtually unknown site near Yonaguni. Several metres beneath the surface lies one of the worldís greatest mysteries, a place that could quite literally rewrite human history.
No one can be entirely sure whatís down there but many experts are convinced itís the remains of a vast and ancient underwater city, a lost civilisation, a Japanese Atlantis.
Kihachiro Aratake made the discovery. He took me to see it.
KIHACHIRO ARATAKE: That is Arakawabana, where the
underwater ruins are located.
SIMKIN: Aratake-san is a professional diver. He was looking for new dive sites when he made the find of a lifetime, in fact the find of several thousand lifetimes, something no human had seen in millennia.
KIHACHIRO ARATAKE: I saw the most incredible thing. It was like my hair was standing on end and I got goose bumps. It was such a shock I didnít believe my eyes. What is such a thing doing under the water?
SIMKIN: At first, Aratake-san kept his discovery secret but now, well aware of the potential for tourism, heís keen to show it off, even when the weather is rough and his guestís diving experience limited.
The water is warm, the current strong. The entire site stretches for kilometres but its centrepiece is three hundred metres long. To reach the monument, as itís now known, you need to pass through an archway, a portal perhaps, to another world, another time.
Giant slabs of stone stand at unusual angles, perfectly parallel. Here what seems to be a drainage ditch, emptying into a small pool. And here a space like a room, carved into the recesses of the rock.
Nearby are the terraces, massive stone steps, all perpendicular. My guide has been diving all over the world for nearly forty years. Heís never seen anything like it. He believes it could be a giant pyramid.
KIHACHIRO ARATAKE: It has the special feature of facing south, the various sections are at right angles and the whole set of ruins is leaning about two degrees to the south. You never se angles like this and everything faces south.
SIMKIN: At the base, twenty five metres below the surface, is a flat clear space with stones piled on each side. Aratake-san thinks it was once a bustling boulevard encircling the site. Everywhere you look there are bizarre shapes and unusual angles. Some claim this is a stylised turtle,, carved out of the rock.
[On boat after dive] Well that is extraordinary, absolutely enormous and almost overwhelming. Very beautiful as well. I suppose the very big question though that needs to be asked is, is it made by humans or have the currents in some way carved all those extraordinary shapes? I donít know the answer but there is a man here who says he does.
Masaaki Kimura is the worldís leading authority on the underwater monument. Heís a professor of marine geology and has dived these waters more than one hundred times. The professor says scientific testing reveals the site is ten thousand years old. Heís convinced the monument is the oldest building on earth, twice as old as the pyramids.
MASAAKI KIMURA: First, if you ask me if it is natural or an artefact, I can say almost 100%, close to 100% that it cannot be made naturally.
SIMKIN: Isnít it possible though, in fact isnít it probable, that these shape occurred naturally and thatís certainly the view some overseas experts take.
MASAAKI KIMURA: We have been able to collect relics, stone tools, relief carvings of animal figures, lithography with characters carved and direct evidence that humans existed. Therefore, as a result, we consider it an artefact.
SIMKIN: There are some striking similarities between the underwater ruins and Okinawaís above water ones, particularly the ancient castles. This is Shuri Jo, ancient heart of the Okinawan empire.
SHURI JO. Click and drag photo to resize.
The shape, size and style, the combination of walls, arches and walkways are reminiscent of the monument although there are key differences. The castle was built with millions of small rocks, the monument was carved out of several enormous ones.
Underwater monument is also cutting the natural monolithic rock, it is very similar.
Parallels, too, with the regionís traditional graves, which were often built beside the sea.
MASAAKI KIMURA: Archaeologists and underwater experts from Europe came to study the site and they suggested it might have been a harbour, a port where ships arrived but the whole thing looks like a temple.
SIMKIN: If thatís true, it means this tiny, laid back island, Japanís most western point, was once home to a sophisticated civilisation thatís since vanished from the face of the earth.
Itís possible the monument was thrust into the sea by a terrible natural disaster but more likely it suffered a much slower fate, the victim of rising sea levels as the ice age ended.
MASAAKI KIMURA: The earth is now getting warmer from the greenhouse effect of carbon dioxide. The monument may be an example of a civilised people that became extinct and perhaps it warns us about the path we may follow in the future.
SIMKIN: Asiaís Atlantis or natureís artwork, hewn by humans or carved by the currents, the monument remains an enigmatic mystery of the deep.