Latitutde: 24.469068 Longitude: 123.001870Website Link
also known as "Yonaguni (Island) Submarine Ruins" (与那国（島）海底遺跡Yonaguni(-jima) Kaitei Iseki), is a submerged rock formation off the coast of Yonaguni, the southernmost of theRyukyu Islands, in Japan.
Masaaki Kimura, Professor Emeritus from the Faculty of Science at the University of the Ryukyus claims that the formations are man-made stepped monoliths. His ideas are disputed and there is debate about whether the site is completely natural, a natural site that has been modified or a man-made artefact. Neither the Japanese Agency for Cultural Affairs, nor the government of Okinawa Prefecture recognise the features as important cultural artefacts and neither government agency has carried out research or preservation work on the site.