The Yonaguni formations really are intriguing - hard to believe they're not manmade but some think they're natural.

Interestingly, Wiki says that, "The local language, which is incomprehensible to Japanese speakers, and even to speakers of other Ryukyu languages is still spoken by a few elderly inhabitants." That could mean that it's a strong dialect, hard to understand, or it might be an unknown Chinese or even Ainu dialect (or a lost language althogether). Not sure if the Ainu were that far south though.