Kaiji Beach (Star Sand Beach)

Kaiji Beach is famous for one thing: its star sand. The tiny star-shaped grains are the exoskeletons of foraminifera, microscopic marine organisms that live in the surrounding coral reef, and they give the beach a texture that is distinctly different from normal beach sand — finer, more angular, and genuinely star-shaped when examined closely. Scooping a handful of wet sand and holding it up to the light is one of those simple moments that stays with you.

Swimming is prohibited at Kaiji Beach due to strong currents that make it genuinely dangerous, unlike the calm waters at Kondoi Beach to the north. The visit is for the star sand and the scenery — a beautiful stretch of coast with a good view of the reef — not for getting in the water. It is a ten-minute bike ride from the village.

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The star-shaped grains at Kaiji Beach are not sand at all — they are the empty shells of a species of single-celled foraminifera called Baculogypsina sphaerulata. The organisms live in the coral reef and, when they die, their star-shaped calcium carbonate tests (shells) wash ashore and accumulate on the beach. Each tiny star is only about half a millimetre across. Taking them from the beach is technically prohibited but widely done; rangers sometimes check bags at the exit. The species is common throughout the Yaeyama reefs, so a few fewer stars on Kaiji Beach doesn't threaten any ecosystem — but leaving them makes the beach more interesting for the next visitor.

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