"When your number is up, your number is up. I actually said that to someone before I went out in the water that day," Mr Johnston told Fairfax Media on Friday.

"For sure I'd do the same thing again. You can't run away from them [sharks]. I just thought about what some divers had told me over the years and kept calm and didn't move.

"I saw some Go Pro footage about a week after it happened. But I didn't see these photos until last night. It wasn't until I saw the photos that I saw how big the shark was - it was in my blind spot when I was in the water, so I couldn't really tell."

The photos were taken by Frits de Bruyn, whom Mr Johnston has not met and believes to have been a Tasmanian tourist holidaying in Esperance.

De Bruyn's Facebook profile lists him as hailing from the Tasmanian town of Longford - which has a population of little more than 7000 people but was thrust into the national spotlight just last weekend when its pin-up horse The Cleaner competed in the $3 million Cox Plate.