Yonaguni Monument

This dive site is the enigmatic Yonaguni Monument, often referred to as the "Underwater Ruins," discovered in 1986 by a local diver. Located about 15 minutes from Yonaguni port, it presents a massive, staircase-shaped rock formation, spanning approximately 250m east-west and 150m north-south. Divers navigate along this unique structure, which some believe to be a man-made ancient city and others a naturally formed geological wonder, offering a mysterious and intriguing underwater exploration. The marine life at Yonaguni Monument is diverse, with frequent sightings of schooling hammerhead sharks, especially during certain seasons. Beyond the impressive pelagics, the site teems with a variety of vibrant reef fish that inhabit the nooks and crannies of the monument's structure, creating a lively ecosystem around the ancient-looking formations. The best time to visit Yonaguni Monument for the chance to encounter hammerhead sharks is typically between November and May. Divers should be prepared for potentially moderate currents, particularly when searching for the hammerheads in the deeper, open water sections. Its relatively shallow average depth of 10 meters and maximum depth of 21 meters make it suitable for both certified scuba divers of all levels and freedivers looking to explore the impressive structures.