Yaeyama Blue Hole

The Yaeyama Blue Hole is a dramatic natural arch and cavern system carved into Ishigaki's reef limestone, where a collapsed ceiling has left a circular skylight that projects a column of deep blue light down into a chamber at 22 metres — an effect most spectacular when the sun is directly overhead between 10 am and 2 pm. Beyond the arch, the outer reef wall drops steeply to beyond sport diving limits, swept by current that feeds enormous schools of barracuda and jacks circling the blue water above. The cavern ceiling and walls are encrusted with dendrophyllia cup corals that thrive in the low-light interior, their bright orange polyps creating a vivid contrast with the blue of the water column outside.