Chugoku's five sites sit along both the Sea of Japan and the Seto Inland Sea, offering reef, cave, muck, and artificial reef diving at moderate depths. The offshore reef at Okinoshima Island, accessed sixty kilometres out by boat, sits at the more challenging end of the range, while shore-entry sites such as Oumijima Naiwan, Omijima Island, and Shikanoshima Island suit beginners. Water temperatures are cooler than Japan's southern regions, dropping to the mid-teens in winter and warming to the upper twenties by late summer. Recorded species include blue-ringed octopus, bobtail squid, butterfly rays, torpedo rays, nembrotha nudibranchs, conger eels, and slipper lobsters.
Monthly water temperature across Chugoku's sites, from satellite sea-surface data corrected for depth. The band shows the site-to-site spread.
Temperatures fall to the mid-teens Celsius in winter and climb to the upper twenties in August and September. The warmest and most comfortable diving runs through summer, while the cooler months suit divers with appropriate exposure suits who want to target the macro species for which the muck sites are noted.
14 operators
Water temperature around Chugoku ranges from about 15°C in February to 27°C in August, based on satellite sea-temperature data for its dive sites.
In the warm season (about 27°C) a rash guard or 3mm shorty is comfortable in Chugoku; in the coldest months (about 15°C) step up to a 7mm or semi-dry suit.
Fin maps 5 sites in Chugoku (3 scuba diving sites).
