Rescue requires a competent diver on site to recover the unconscious diver to the surface, or prevent them from sinking in the case of a surface blackout. This requires that the safety diver is aware of the status of the diver in time to react effectively. The unconscious freediver should be brought to the surface with minimum delay. There is no risk of lung over-pressure injury, and the airway should be secured if possible to prevent aspiration. The mask is adequate protection of the nasal passages if in place, and a hand can be used to cover the mouth and hold it closed.