Boston University's Schoch, meanwhile, is just as certain that the Yonaguni formations are natural.
He suggests that holes in the rock, which Kimura believes were used to support posts, were merely created by underwater eddies scouring at depressions.
Lines of smaller holes were formed by marine creatures exploiting a seam in the rock, he said.
"The first time I dived there, I knew it was not artificial," Schoch said. "It's not as regular as many people claim, and the right angles and symmetry don't add up in many places."
He emphasizes that he is not accusing anyone of deliberately falsifying evidence.
But many of the photos tend to give a perfect view of the site, making the lines look as regular as possible, he said.
Schoch also says he has seen what Kimura believes to be renderings of animals and human faces at the site.
"Professor Kimura says he has seen some kind of writing or images, but they are just scratches on a rock that are natural," he said.
"He interprets them as being manmade, but I don't know where he's coming from."
But Kimura is undeterred by critics, adding that the new governor of Okinawa Prefecture and officials from the United Nations Educational, Scientific, and Cultural Organization have recently expressed interest in verifying the site.
"The best way to get a definitive answer about their origins is to keep going back and collecting more evidence," he continued.
