I forget where I stumbled across this, but a couple years ago I read about this underwater archaelogical expedition off of the Japanese island of Yonaguni that looked man-made. I was reading about the escalating tensions between Japan and China and Yonaguni was mentioned as an extent of Japanese territorial claims and thought… Yonaguni… that sounds awfully familiar… OH YEAH, that’s where that mysterious underwater rock formation is *search* *search* *search* sure enough, that’s what I was thinking of.
In the 1980s, local divers discovered a striking underwater rock formation off the southernmost point of the island. This so-called Yonaguni Pyramid consists of staircase-like terraces with flat sides and sharp corners.
In 1985, Kihachiro Aratake, a diver from Japan, was diving in the waters off the Southern shore of Yonaguni island and discovered something unusual. Upon inspection, it appeared to be a man-made, terraced structure. Believing he had discovered a sunken city, Aratake announced his discovery, but there was not much interest. Later, in 1996, Professor Masaaki Kimura , a professor at the University of the Ryukyus, began to survey the structure. While Kimura maintains that the site is evidence for an advanced prehistoric civilization, others argued that the structure was the result of natural phenomena. Research in the ensuing years has arrived at a consensus that the structure is indeed a man made monolith carved from a natural formation.
Something I missed on the first round of investigation was that the endpoints extended from the various cuts in the rock correspond roughly with the limits of territorial expansion of the Japanese Empire during World War II.
I dunno, I think that’s kind of a stretch, but who knows.