on a good seal between the administration mask and the casualty's face. Nasal cannulas provide inspired oxygen fractions only slightly more than air, and are not of much benefit to injured divers. Air breaks are not necessary to avoid oxygen toxicity at surface pressure. Emergency oxygen supply Sufficient oxygen to provide two divers with 100% oxygen at 15 litres per minute for long enough to reach further supplies of oxygen is standard equipment for commercial diving operations under the Scientific and Inshore codes of Practice in South Africa. Extrication and transportation equipment An injured diver may need to be removed from the water in an inconvenient place, and special equipment such as a stretcher, spine board, high-angle rescue equipment or recovery slings may be required to get the casualty to a place more suitable for first aid, or to a vehicle for transportation to medical facilities. Emergency services Coast guard and sea rescue services, ambulance and paramedic services, mountain rescue services etc. may be involved in the later stages of a diver rescue operation. Rescuers and training In recreational diving, the urgency of the rescue and the remoteness of dive sites mean that professional rescuers rarely take part in diver rescues. Other divers at the scene become rescuers. As the immediate in-water rescuer is often the diver's own buddy, recreational diver training agencies often teach rescue techniques in intermediate-level diver training courses; examples are the PADI Rescue Diver, the BSAC Sport Diver and the DIR Rebreather Rescue courses. Professional divers are usually trained in diver rescue for the modes of diving they are certified in, as part of the work of a professional diver is as stand-by diver to the working diver. The level and quality of training and required skill for certification may vary depending on the jurisdiction and relevant code of practice. During professional diving operations there will usually be a competent diver on stand-by at the surface control point, or in the water with the working diver, or both. The surface stand-by diver should be ready for immediate deployment for a rescue if this is deemed necessary by the diving supervisor, who is responsible for the safety of the dive team and for managing a rescue. Appropriate equipment based on the operational hazards and risk should be available on site. The bellman is the in-water standby diver in wet and dry bell operations. See also References External