Yonaguni Monument

The Monument is a mass of layered sandstone the size of a building, cut into flat terraces, straight edges, and stark right angles, found in 1986 by local diver Kihachiro Aratake while scouting hammerhead grounds. Whether people shaped it is a genuine, unresolved argument. Marine geologist Masaaki Kimura spent years cataloguing what he interpreted as tool marks, drainage channels, and even carvings; most geologists respond that this sandstone naturally fractures along horizontal bedding and vertical joints, producing staircase forms without any hands involved, and that similar geometry appears on the island's shoreline. Diving it, you sweep across the main terrace, duck the surge behind the prow-like corner, and understand why both camps sound so sure of themselves.

您此行的高光时刻: The terraces and right angles themselves, the natural-versus-carved debate, big Kuroshio visibility

地形地貌: Massive stepped sandstone formation rising from about 26 m toward the surface

水流: Kuroshio-driven flow and surge over the terraces are routine; calm days are the exception to plan for.

入水方式: Short boat runs from the island's harbors; entries are timed around surge and the current wrapping the south coast.

危险因素: Surge over the terraces, current at the corners, and swell surface intervals; listen hard to the local briefing.

高氧（Nitrox）: 在此值得使用——各潜点深度落在富氧空气（nitrox）能有效延长免减压时间的区间（前提是持有相应认证）。