Underneath the waters off Yonaguni-jima, Japan's westernmost point, is an enormous series of ancient stone structures believed to have been a settlement that dates back to 8,000–10,000 BC, which would make it the oldest—by 5,000 years—human structure of this sort. The site has become popular among divers, especially because schools of photogenic hammerhead sharks migrate through the area in winter. Marlin fishing here is also highly rated. Yonaguni-jima is known for wonders above ground, too: unusual rock formations, the Yonaguni atlas moth, the world's largest moth species with a 24-cm (9½-inch) wingspan (don't worry, they're not scary but beautifully colored with intricate designs), and wild Yonaguni ponies. To get to Yonaguni-jima, you can fly via JTA from Ishigaki-jima or Naha.