Koshimoda Asuka Oki

Koshimoda Asuka Oki (小下田・飛鳥沖) is a boat-dive site off Asuka, a little south of Saku Ne, at Toi, Izu, on the west coast of the Izu Peninsula in Shizuoka, for advanced divers, with strong current at times and frequent rough seas except in light easterlies. Opened in 1991, it centres on a pair of hidden pinnacles lying north and south; the boat moors on the northern one, whose top is at about 6 m, while the southern top is at about 15 m, and both fall away to 40–50 m. The terrain between them is a maze of rocks, channels and holes, with walls of chicken grunt, jack and takabe year-round, sweepers in the holes, boarfish in the channels, and amberjack, yellowtail amberjack, rainbow runner, eagle ray schools and thresher sharks in summer and autumn.

Confirmed by our research team, reported by independent divers, or observed nearby via iNaturalist — each entry is labelled with its source.

• Hilgendorf's SaucordHelicolenus hilgendorfiiReported here · unconfirmed
• Slender Lettuce CoralLeptoseris mycetoseroidesReported here · unconfirmed