Idesari

Idesari, also known as Ga Hana, is a boat dive site on the east side of Hachijō Island, located less than 10 minutes from Kaminato port. It sits among a series of coastal sites shaped by volcanic activity, and its defining feature is a set of spectacular volcanic rock arches that form the core of the dive.

The bottom is volcanic rock, with a maximum depth of 25–30 m. Much of the interest is concentrated at 20 m and shallower, where the arches are covered in life. Fields of anemones and seagrass spread across the site, with hard coral formations appearing in the shallower sections of the arches.

The arches support a wide range of marine life, including reef fish, nudibranchs, and hard coral. Tuna and skipjack appear on days when the site is exposed to open-water conditions, and a large school of batfish is seasonally present in the area.