to a place of safety at effectively the same pressure at all stages. First aid and urgent medical treatment must also be done in the hyperbaric environment. It is not practicable to decompress from saturation outside of a hyperbaric chamber, as the decompression generally takes several days. Rescue of a diver and recovery to the bell by the bellman is relatively straightforward, and much like the case for a wet bell. Hoisting tackle is provided to lift the casualty into the bell through the hatch, using the lifting points on the harness, and the bell can be partially flooded to assist with buoyancy. Once both divers are back in the bell, and the umbilicals stowed, the bell can be sealed and lifted while first aid is administered, and the divers transferred to the accommodation chambers for further treatment by the diving medical technician under instructions from the hyperbaric physician. Rescue from a disabled bell usually involves another bell capable of the same depth. Divers will generally transfer between bells at or near the bottom at ambient pressure. It is possible in some circumstances to use a bell as a rescue chamber to transport divers from one saturation system to another. This may require temporary modifications to the bell, and is only possible if the mating flanges of the systems are compatible. Rescue from a saturation system in imminent danger is generally known as hyperbaric evacuation, and generally makes use of a hyperbaric lifeboat or rescue chamber to transport the divers and a hyperbaric reception facility where divers can be decompressed and treated in relative comfort. Evacuation of a single diver who is medically stable, or a single diver with an attendant, may be possible using a hyperbaric stretcher or a small portable chamber if the duration of the trip is short, the pressure is suitable and the mating flanges are compatible. Precautions during the rescue Rescuers should not take unacceptable risks; any rescuers who become casualties themselves may jeopardise the rescue of the original casualty particularly as many of the emergency resources available at dive site, such as rescue manpower, first aid oxygen, underwater time and gas are generally in short supply. Conscious casualties may panic and put the rescuer's safety at risk particularly when the rescuer approaches a casualty in or under the water. It may be possible to avoid contacting a panicked casualty by throwing a rope or