A man attacked by a shark on Saturday morning off the north Queensland coast owes his life to quick thinking friends who applied a tourniquet to his mauled leg, Queensland Ambulance Service said.
Three people on a boat dragged the injured man from the water after he was attacked by a shark moments after diving into the water to go spearfishing.
One of the friends, who has previous experience in the military, applied vital first aid before the victim was airlifted to Cairns Hospital in a critical but stable condition.
Martin Taylor from the Queensland Ambulance Service said the victim owed his life to friend's quick actions in applying the emergency tourniquet, which stopped the bleeding.
"The initial actions by three friends have definitely saved his life ... because he was losing so much blood," he said.
QAS Cairns senior operations supervisor Neil Noble said the patient was awake and talking heading into emergency surgery in hospital.
"Miraculously he may have a very positive outcome," Mr Noble said.
The man, understood to be 26 years old, but previously reported as being 19, had been spear fishing off Eva Island near Hinchinbrook Island, 165 kilometres north of Townsville, when he was attacked.
The victim jumped off the rocks and into the water where he was bitten multiple times on the leg by what is believed to be a tiger or bull shark, according to reports from the scene.
His three friends were in the water at the time of the attack and dragged him back onto their boat before calling emergency services just after 10.30am.
The boat them returned to the mainland, meeting paramedics at the Port Hinchinbrook boat ramp where he was stabilised.
A rescue helicopter arrived on scene just before midday and it is understood the victim had lost a significant amount of blood, with the worst of the injuries limited to just one leg.