From afar it looked like a minor wipe-out, but for 70 frightening seconds bodyboarder Justin Firgaira was out cold underwater.

Even his bodyboard failed to resurface for 20 seconds — both had seemingly washed off the face of the Earth.

Firgaira was surfing at Knights Beach in Port Elliot, south of Adelaide — one of the district's heavier beach breaks — with his longtime friend, Brad Halstead, last Wednesday.

"Most of the waves are closeouts, but on certain sets you get a wedge that comes across and it sometimes makes a right-hander or a left, and I was trying to go for the right," Firgaira said.

Firgaira thinks his head hit the sand before he and his board were swept into a deeper pocket of water closer to a headland where the rips were strong.

"Obviously being concussed and unconscious I'm not fighting to come back up," he said.

"But even the board was underwater for a good two-wave set, so there was essentially something holding it down there."

Surfing is still allowed in South Australia despite COVID-19 restrictions, and the two friends spent some time searching for a break with only a few people in the water so they could maintain physical distancing guidelines.

The swell that day was up to five feet high, but the wave that knocked Justin out — as captured by Swellnet's local surf cam — was a smaller one he regarded as "nothing special".

Follow the tombstone

Out beyond the breakers at Knights, Halstead was struck with a sense that something "wasn't right".

The two had already discussed going in after one more wave, so it made sense that his mate had headed for shore.

"But I had a gut feeling that something wasn't right, and it had me continually looking for him," Halstead said.

"When his board finally popped up, I saw that it was it was tombstoning [sticking upright to bob about in the water], and thought, 'Oh shit — he's in trouble'."

The board quickly disappeared back underwater again, before tombstoning again 15 seconds later and floating away after its leash slipped from Firgaira's arm.

Increasingly fearful for his friend of 27 years, Halstead did his best to reach where he thought Justin might be, but the rip was holding him at bay and the waves threatened to push him the wrong direction.

He eventually caught a wave that would drop him where he thought Firgaira could be.

"He was completely submerged about a metre away, but I couldn't see him," Halstead said.

As Firgaira started sinking again, Halstead pulled his friend's head out of the water and noted that his face was "white, but it hadn't turned blue".

The waves continued to smash over them, giving Halstead no option but to "bear hug" his friend to stop him from being pulled away by the rip.

Slowly kicking them both towards shore, they were joined by other surfers and an onlooker desperate to help.

'Why are you hugging me?'

Firgaira, who was diagnosed with mild concussion and a perforated eardrum after the incident, said he did not remember much at all.

But he does recall waking up in knee-deep water in the arms of his friend.

"And I'm asking questions like, 'What's going on? What happened? Why are you hugging me?'" he said.

A small graze behind Firgaira's right ear shows where his head hit the sandbank and knocked him out, but what surprised both men was the lack of water in his lungs.

History is studded with stories of people surviving, unconscious, for long periods underwater.

This is often attributed to a survival response known as the mammalian diving reflex, which can lead the body to hold its breath, slow the heart rate, and divert oxygen-carrying blood to the parts of the body that need it most — the same reflex that leads a newborn to hold its breath and swim underwater.

Firgaira recovered so quickly that the friends went for food before he went home to his wife, Beverley, a nurse who eventually took him to hospital.

The balance between drowning and any instinctive response to the risk of drowning, however, is incredibly slim, and Firgaira is under no illusions about his luck.

"I'm looking at investing in a helmet, just to get my confidence back up for those larger swell days," he said.