Conditions & tides
Scored by DiveConnect's site-physics model
Marine forecast via Copernicus Marine. Score is a rule-based guide from swell/wind vs. the site's exposure — always dive your own assessment.
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About this site
One A (大根A) is a boat-dive site at Nishikawana in Tateyama on the Boso Peninsula, Chiba, four minutes from the harbour, with a maximum depth of 24 m. From the A buoy a guide rope leads to the so-called V-shaped valley at 18 m, where the sandy floor holds bearded grunt, longtooth grouper, striped beakfish, scorpionfish and rockfish through the year. Intermediate and above. The A buoy is also the starting point for Nishikawana's signature spots, the eagle ray reef and the shark hole, with schools of banded houndsharks and eagle rays gliding overhead from May.
Marine life here
Confirmed by our research team, reported by independent divers, or observed nearby via iNaturalist — each entry is labelled with its source.
Pearl-spot ChromisChromis notataReported here · unconfirmed
Blacksaddle GoatfishParupeneus spilurusReported here · unconfirmed
Durable tips from divers — access, hazards, marine life, facilities. For day-of conditions, use the report tool in the conditions card above.
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