Hachijojima

Before Entering

• Use a recognized local dive operator, give accurate certification and recent experience, and follow its site-specific entry and abort instructions. Seek the shore entry appropriate to that morning's wind, swell, tides, current and harbor movements.
• Treat Nazumado and exposed boat sites as advanced unless an experienced local guide specifically accepts the route and diver profile. A protected Yaene or Sokodo entry can still have boat traffic, rip currents or dangerous surf.
• Confirm a guide's oxygen, first-aid, missing-diver and evacuation plan. Carry a suitable surface marker buoy, audible signal and appropriate thermal protection when advised. Do not assume constant mobile coverage offshore.
• Remain outside cave/cavern overheads unless separately trained and appropriately equipped, and never penetrate or touch the exterior-only Chinsen wreck. Avoid fishing nets and lines; do not remove organisms, shells or coral.
• Breath-hold sessions require a competent active buddy, direct supervision and an agreed rescue plan. Never hyperventilate or dive alone; no source established a year-round dedicated freediving safety operation.
• For snorkelers, use the authorized Sokodo swimmer zone and obey blue/yellow/red daily flags in the staffed season. Never assume a colorful reef, a calm moment or a turtle sighting makes offshore swimming safe.

After Diving and Transport

DAN's general flying-after-diving guidance recommends at least 12 hours after a single no-decompression dive, at least 18 hours after repetitive or multiday no-stop diving, and longer after any decompression exposure. These are minimum guidelines, not a guarantee; your computer, dive profile and medical circumstances may call for more time. Discuss any possible decompression illness urgently with local emergency services and a qualified dive medical service; do not board a commercial flight to seek care without medical coordination.

Hachijo Municipal Hospital in Mitsune is the verified island general medical facility (04996-2-1188). For immediate ambulance assistance in Japan call 119; for sea emergencies use Japan Coast Guard 118. The hospital website does not establish an operating hyperbaric recompression chamber on Hachijojima, and none was independently verified. A serious dive injury may need remote expert advice and mainland transfer, which can be affected by air/sea weather. Ensure evacuation/recompression coverage, disclose relevant medical conditions and have a clear access plan for the selected shore or boat site. For suspected decompression illness, provide oxygen if trained and equipped and seek urgent professional medical direction. Do not rely on any guarantee of a same-day mainland flight or boat.

Hachijojima is within the Fuji-Hakone-Izu National Park region, but that designation does not automatically create a general scuba park-tag payment system. Follow actual restricted-area signs, approved access, fishing rights and park controls. The Tokyo Hachijo branch restricts collecting shellfish, algae, lobster and other marine resources under local fisheries rights and prohibits certain capture methods, including use of scuba gear and underwater spearguns for seafood collection. Look, photograph without damage, and leave animals and habitat in place. Never handle turtles, coral, nudibranchs or fish, block an animal from surfacing or pursue whale sightings. Whale-watching advertised for winter is a boat-based observation program, not a permission to enter water with cetaceans.