Boso Peninsula

Site Selection and Qualifications

At Ito, use only the qualified operator boat excursion: BOMMIE requires AOW, 30 logged dives, a dive within one year, boat experience and calm mask/regulator recovery. It warns of currents at the surface and descent rope, especially July-October. Do not touch or feed sharks and rays; controlled feeding is done by staff. For Namegawa Maguro-ne and Katsuura boat reefs, request a site-specific current and depth briefing. Cavern-like overhangs and wrecks do not confer overhead-entry privileges.

Swimming and Breath-hold Safety

Tateyama City explicitly lists Okinoshima north/west, Heisura and Mera as dangerous swimming zones. Shallow water can still have fast drift. Snorkel only with appropriate support, in approved sections, and do not use the Ito fishing/boat site as a snorkel entry. Breath-hold training requires rescue-capable buddy/instructor observation and no solo attempts. Check JMA storm and tsunami warnings and local evacuation notices.

For acute injury or suspected decompression illness, call 119 first, or 118 if a maritime rescue is needed. Administer appropriate emergency first aid including oxygen if trained and equipment is available, and follow emergency medical instructions. DAN Japan has a member emergency advice line but is not a substitute for dispatch. Chiba Prefecture lists emergency hospitals including Shioda Hospital in Katsuura and Awa-area centers. No exact recompression chamber, chamber operating hours, travel-time or emergency-transport guarantee was independently verified for this research. Confirm operator oxygen provision, boat communication, nearest accepting hospital and recompression pathway before technical or multi-day dives.

Ito is a provisioned wildlife dive created in relation to local fixed-net fisheries; guests must not feed, strike, grab or crowd sharks and rays. Follow guide instruction and avoid stressing animals for photographs. Around Okinoshima, Tateyama identifies special protected park vegetation, eelgrass and near-limit coral habitat. Chiba Prefecture prohibits taking specified fishery-rights shellfish and other protected marine animals without authorization, including abalone in prohibited contexts. Do not spear fish, take live shells or collect wildlife, damage corals/sea grasses, litter or trespass in harbors and military-base boundaries. The optional Okinoshima conservation donation does not purchase collection rights.