Near drowning occurs when someone revives a diver or Swimmer who became unresponsive (unconscious, or unable to respond or act coherently) and stopped breathing while submerged. Swallowing water, extreme fatigue, entanglement and long over pressurization may be the cause, with panic, inefficient breathing, throat blockage, exhaustion, heart stoppage and unconsciousness contributing. 

With an unresponsive diver, the primary concern is to check for breathing and to begin rescue breaths if the isn't breathing. If a diver is unresponsive underwater, bring the diver to the surface; someone may need to perform rescue breathing in the water, and if the victim has no pulse, CPR. You can't perform CPR effectively in water, so you need to get the diver out of the water.

Here are the four general procedures to follow if a diver appears to lose consciousness and becomes unresponsive in the water:

1. Quickly bring the diver to the surface and check for breathing.
2. Establish ample positive buoyancy for you and the victim.
3. Get assistance as needed in providing rescue breathing.
4. Help remove the diver from the water.

Assistance continues once out of the water, with the following steps also applying to a diver who, after diving, becomes unconscious or experiences symptoms of lung over expansion injury.

These symptoms may include difficulty breathing, confusion, lowered alertness, a change in the level of consciousness, unclear thinking, visual problems, paralysis, and chest pain.

Keep airway open and check for breathing. If necessary, start and continue rescue breathing and/or CPR.Observe the diver constantly, checking breathing and pulse.If the diver doesn't require CPR or rescue breathing, keep the diver lying level on the left side supporting the head (called the recovery position). Don't let this position interfere with transportation or other aid, and should not be used :CPR is required. If the diver is responsive and more comfortable lying prone, that's fine.

Administer emergency oxygen if possible.

Keep the diver still and maintain a normal body temperature by protecting the diver from heat or cold.Seek emergency medical assistance.If unable to accompany the diver to medical treatment, write down as much background information as possible and attach it to a conspicuous place.