Eric Nerhus is almost certainly Australia's luckiest man.
He was diving for abalone off Cape Howe south of Sydney when a 3-meter great white shark attacked.
It clamped its jaws down on his head, crushing his face mask and breaking his nose.
Nerhus initially managed to escape after gouging his fingers into the predator's eyes.
As he struggled to get away the shark attacked him again, this time grabbing him by the body and inflicting deep cuts.
In a remarkable act of survival, he again managed to free himself and was hauled back aboard his boat by his son, Mark Nerhus.
"He come up to the surface and he was going 'Oh! Help, help! There's a shark, there's a shark!' and I went over there and there was a big pool of red blood and I pulled him out of the water," the son said.
The diver was airlifted to a hospital, where he is in a serious but stable condition, suffering from blood loss and shock.
Fellow divers say several great white sharks, also known as white pointers, had been spotted in the area recently due to unusually cold waters.
They think the victim was probably mistaken for a seal and said the attack was unusual.
Sharks have killed 10 people in Australia since 2000.