Andy Nelson and Tim Ryan were hunting for crayfish off the coast of Safety Bay, Western Australia, when they came dangerously close to a great white shark.

The four-metre ocean predator lurked just a few meters away, circling for five minutes while the companions swam at low altitude, trying to stay calm.

“He gives me the shark signal with great enthusiasm. I turned around and I still have this image of a very large shark’s head above me,” Nelson told 9News.

Ryan remembers being close enough to touch the shark.

“It came right over my head, like that, with my mouth a little open, I could have reached up and touched it,” he said.

“I was definitely like yeah, we were a little worried.”

As if that wasn’t stressful enough, while the two men were 10 meters below the surface, Ryan’s oxygen tank began to empty.

“I was running lower and lower in the waves by the minute,” he said.

“The one thing you don’t want to do is walk away from a white pointer, because your feet while doing that (paddling) are like bait.”

The fly in fly out service worker was ultimately forced to make an ascent without air.

A shark scientist praised the two men for their response, crediting their experience and saying their calm was key to their survival.

“There is safety in numbers, always keep one eye open and face the animal and try to stay calm and avoid any irregular movements,” shark scientist Dr Leonardo Guida told 9News.

The two companions are now linked for life by their moving encounter.

“Friends don’t come any closer than that,” Ryan laughed.

“We feel really lucky to have the chance to interact with a huge predator,” Nelson added.

“So we were very lucky.”