Adrian Bullock says the safety of nearby snorkellers was his priority when he came face to face with a great white shark off Lady Elliot Island near Bundaberg last week.
"I screamed: 'White shark! White shark! Get out of the water!'" the photographer recalled, adding that he quickly overcame his fears to film the rare encounter.
Battling to steady his heart rate and breathing, he said he managed to get out his camera and film and photograph the creature.
Although far from relaxing, he said the interaction was thankfully peaceful.
"It's so amazing," he said, adding that he believed it was only the second recorded sighting of a great white near the island in 25 years.
The four-metre shark came within three metres of Mr Bullock during an advanced snorkelling safari.
He said the video made the encounter look far more relaxed than he felt.
"My heart sunk and I was in a bit of shock at first," he said.
"It got to within three metres of me and I realised then it was either very full or pregnant."
He said he visited the island once a year and the close encounter had made him excited to return.
"I look on it and I enjoyed the moment; it was very emotional, but I can laugh and smile about it now.
"I feel very proud to have been the one to be chosen by the shark to have a swim with.
"I'm not sure anyone really believed me when I first got out of the water, but once they all saw the video they knew exactly what it was."
