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Amami Guntō NP, Kagoshima
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A tiny hermit crab in Oshima Strait skips the usual seashell: it lives inside a living “walking coral” and carries the coral as it moves, helping keep its home from being buried.
On June 4, 2026, branching corals in Oshima Strait released countless pale-pink bundles of eggs and sperm. They floated up through the night water, coloring the sea like a rosy cloud.
Humpback whales visit Amami’s waters from January to March, traveling south from northern feeding grounds to mate, give birth and raise calves. Oshima Strait lies in their winter range.
Oshima Strait’s bluefin farms supply local tables, and Setouchi turns tuna stomach into maguro chanja, a savory specialty that won a Fisheries Agency award. A tuna bowl is another local favorite.
Amami’s first mabe-pearl ventures began in 1910 at Yui Kojima and Tawarakojima, in today’s Setouchi Town. Unlike round pearls, cultured mabe pearls are characteristically half-round.
Oshima Strait is only 2–6 km wide but more than 50 m deep. A branch of the Kuroshio Current enters through its opening, where distinctive inner-sea coral reefs have developed.
At the strait’s western entrance, Nishikomi’s Asa Toramatsu organized 22 neighbors into a skipjack-fishing cooperative in 1900. By 1904, Amami’s fleet had grown to 138 boats.
A group drive-net fishery came to Setouchi from Okinawa’s Itoman area around 1913. In this coral-reef method, crews work together to herd schooling fish into nets; a 2011 prefectural profile counted 2 local groups.
On big-tide nights, people lit torches to gather fish, shellfish and octopus on the reef flats. In interviews, residents recalled a day’s catch of as many as 200 spiny lobsters and 100 turban shells.
At Nominoura Bay on Kakeroma, a base for Shinyo special-attack boats was built in World War II. Its commander was novelist Toshio Shimao; his wartime experience became a source for his writing.
At Nishikomi, the old gun observation post has a painted guide to the view: its wall shows islands and reefs visible from the lookout, with distances marked for observers watching the strait.
At the eastern entrance, the Ankyaba fortification used controlled mines beneath the water to stop enemy ships. A guard station listened and kept watch over the entrance.
A brick water reservoir built at Kuji in 1890 supplied ships anchored offshore in Kuji Bay. Small cutter boats carried the water out; the reservoir is the oldest military-site ruin on Amami Oshima’s main island.
Across the strait, villages on Kakeroma, Ukejima and Yoroshima preserve traditional walls made from coral. They’re a striking reminder that the reef is part of the islands’ lived-in landscape, too.
For hundreds of years, ships have sought refuge in Oshima Strait from typhoon winds and high waves. Its winding ria coastline creates sheltered inlets within this narrow passage.
After high temperatures in 2024 killed about half the shallow-water corals around Amami, Oshima Strait was cooler than nearby waters and suffered less bleaching. Some valuable branching-coral colonies survived.
