difficulty. Reasons for needing rescue There are many reasons why a diver may need rescue. These generally imply that the diver is no longer capable of managing the situation. Scenarios requiring rescue include: running out of breathing gas inability to access the breathing gas due to an equipment failure unconsciousness inability to see the depth gauge or diving computer to make a safe ascent, generally because the diving mask is lost, keeps flooding or is damaged panic incapacitated due to trauma, diving disorder, or other medical condition becoming lost or trapped underwater inability to control buoyancy and/or inability to apply thrust sufficiently to ascend (in Scuba diving without a lifeline) inability to return to the shore or a boat after a dive hypothermia narcosis exhaustion The diver may get into a situation requiring rescue through incompetence, unfitness or bad luck. Rescue activities The effort and difficulty of a rescue varies widely and depends on many factors such as the nature of the problem, the underwater conditions and the type and depth of the dive site. A simple rescue could be to tow to safety a diver on the surface who is exhausted or suffering from leg cramps. A complex and high-risk rescue would be to locate, free and bring to the surface a lost diver who is trapped underwater in an enclosed space such as a shipwreck or cave with limited breathing gas supplies. The sequence of potential activities needed in a generic rescue are: Recognising or identifying the need for a rescue if the casualty's position underwater is unknown, locate the casualty and, if possible, mark the position if the casualty is low on breathing gas, provide more gas if the casualty is trapped, free the casualty if the casualty is submerged, bring the casualty to the surface if the casualty has a decompression obligation, decompress if safely possible. The rescuer must also take into account their personal decompression requirements. if the casualty is not buoyant at the surface, make the casualty buoyant if help at the surface is available but not at hand, attract help if the casualty is not breathing, carry out continuous artificial respiration on the surface if the casualty is on the surface in the water and no help is available, tow the casualty to a boat or to land if the casualty is beside a boat or the shore, remove the casualty from the