Japan's best cave topography, 'Devil's Palace' (Ma-ga-ma) is a vast chamber with three exits and shafts of blue light, and…Japan's best cave topography, 'Devil's Palace' (Ma-ga-ma) is a vast chamber with three exits and shafts of blue light, and 'Antelope Cave' a 40m vertical shaft you ascend into an air chamber. Miyako's limestone is riddled with arches, tunnels and swim-throughs on a scale nothing else in Japan matches. Miyako's caves formed when Ryukyu limestone was above sea level during the ice ages, then flooded, the stalactites in the air chambers are the proof. Japanese cave divers mapped the system through the 1980s and 90s, and the sites now anchor Miyako's dive industry. Anchorage: Anchor off Irabu or use Hirara port; the sites are along the Shimoji coast. Hazards: Genuine overhead environment, cathedral-scale but still cave diving. Local guide mandatory. Typhoon season Jul-Oct. Plus