A group of young men dragged a 69-year-old man from the water off Coalcliff rock pools and administered CPR until ambulance crews arrived.
Around 2pm on Thursday, the 69-year-old swimmer suffered a heart attack in the water and was submerged for around a minute and a half.
Ambulance NSW Inspector Norm Rees said several young men rushed into the water and dragged the man out, while two others raced to the nearby surf club to get the defibrillator.
Instead of using the defibrillator the men carried out CPR, with the help of an off-duty paramedic who was nearby.
When the three ambulance crews - including a Special Operations Team - arrived, they found the man had a collapsed lung and possible spinal injuries.
It is not confirmed how the man suffered the injuries but it is suspected he may have been pushed into rocks while underwater.
The initial plan was to airlift the man to St George Hospital on the Toll Rescue Helicopter, however due to the possible spinal injuries he was flown to Royal North Shore Hospital in a serious and unstable condition.
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