Izu Oshima

Mandatory Local Preparation

• Follow site boundaries, any seasonal no-dive period, dive flag procedure, council member-shop tank sourcing, one SMB per diver and an attached dive computer.
• For Keikai early mornings, meet the council minimum of 30 logged dives, complete a regular island dive first, sign the declaration, and supply a physician certificate when required by age or medical history. Operators may impose stronger requirements.
• Use a qualified local guide for current-sensitive points, unfamiliar lava entries and specialist boats. Carry an exit contingency and end a dive early if the planned shore return becomes unsafe.
• Never enter tunnels, caves, overhangs or other overhead environments on an open-water qualification. A surface arch viewpoint is not cave-diving authorization.
• For breath-hold water activities, do not hyperventilate, dive solo or assume a scuba instructor automatically offers advanced freedive rescue.
• Delay or cancel all water activity for tsunami advisory, official swim prohibition or unsafe storm/surge conditions. Council rule sheet; Keikai criteria.

Dives and Return Transport

DAN minimum surface intervals before flying are context-dependent; multi-dive trips generally need at least 18 hours, and many travelers build a longer margin. Do not schedule a quick Chofu flight immediately after diving or interpret a general interval as a guarantee against decompression illness. DAN travel guidance.

Oshima Medical Center is the documented Motomachi medical facility, with main published contact +81 4992-2-2345; its published routine outpatient schedule is not proof of around-the-clock specialty care. No island recompression chamber or diving-medicine service was verified in the official information reviewed. Suspected decompression injury, serious immersion incident, chest pain, altered consciousness or major trauma requires emergency services immediately. Call 119 for ambulance, or 118 for an offshore maritime emergency. DAN Japan operates a 24-hour hotline for members at +81-3-3812-4999, after emergency service contact, and can help direct doctors toward appropriate specialist treatment. Evacuation to the mainland is possible in principle but depends on clinical priorities, weather, shipping or aviation availability and emergency authority decisions. Official center listing; DAN emergency advice; 118.

The island's volcanic coast is a working fishing landscape, not an open-access aquarium. The Oshima Diving Council rules prohibit capturing shellfish, lobsters, seaweed or other marine life and prohibit fish feeding and physical damage to marine organisms. Respect fishing operations and registered dive areas; never spear fish during casual breath-hold recreation or remove shells and underwater specimens. Use established entry points, avoid touching corals, and keep litter out of coastal waters. Follow any updated temporary fisheries or marine-use restrictions; a photo of a site is not a legal access permit. Council stewardship rules.