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Iriomote Ishigaki NP, Okinawa
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Unlike most corals, blue coral’s skeleton is naturally blue. Shiraho’s enormous colony is described in Japan’s national park plan as the largest-scale blue-coral community in the Northern Hemisphere.
Shiraho’s “micro-atolls” are coral islands in miniature: massive colonies grow sideways when their tops reach the low-tide limit. Some local Porites are 2–3 m high and 3–5 m across.
At low tide, Shiraho’s farming families gathered seaweed, shells, octopus and shrimp from the reef. It fed people through drought and wartime, earning elders’ names for it: the “treasure sea” and “life-sustaining sea.”
Shiraho once had 16 stone fish weirs called inkachi: high tide let fish inside, and the ebb trapped them. In 2006, local children, families and conservationists rebuilt a 400 m weir for learning and Sanizu.
On lunar March 3, Shiraho observes Hamakudari, or Sanizu. Women once purified themselves in seawater and laid coral stones around a family gathering place; the custom continues today in a changed form, without the stone fence.
Shiraho’s sheltered reef lagoon is called the ino, and it was traditionally a village commons. Outsiders could not simply harvest its fish: they had to pay the community’s fishing fee, called umigane.
In 1979, Okinawa proposed a 2,500 m airport runway over Shiraho’s reef. After years of relocation and debate, the 2000 site decision chose an inland Karadake plan instead.
After a fish-weir lesson, Shiraho middle-schoolers proposed planting greenbelts around farms to keep red soil from washing into the reef. Their idea sparked a community project linking fieldwork directly to coral conservation.
At Shiraho’s harvest festival, dancers perform to songs about fishing in the coral sea—a striking pairing in a celebration of crops, and a reminder of how closely the village’s fields and reef are tied in local life.
Coral doesn’t stop at the waterline: reef stones became village walls, house foundations, stepping stones and well rims. Traditionally, even the white plaster holding red roof tiles was made by burning coral.
At Shiraho’s sacred sites, called utaki, devotees place fresh white sand from the sea in incense burners when they pray. The reef’s sand thus has a place not only in food and homes, but also in local worship.
