An unnerving picture of an enormous great white shark following a kayak in South Africa has gone viral.
The image was taken by researcher Thomas Peschak, who, along with his friend, biologist Michael Scholl, started tracking white sharks from kayaks, as other boats disrupted the shark's natural behaviour with their engines.
On his website, Thomas described the first few attempts as "a little nerve-wracking", adding: "It is hard to describe what goes through one's mind when sitting in a yellow plastic sea kayak and a 4.5m great white shark is heading your way".
But he added that sharks are "cautious and inquisitive" and "at no time did any shark show any aggression towards our little yum yum yellow craft".
A number of people have suggested this picture is fake, but Thomas insists it is 100 per cent the real deal.
He said: "The photograph is real, no photoshop, no digital manipulation, no nothing, in fact it was shot on slide film Fuji Provia 100 using a Nikon F5 Camera and 17-35 mm lens. For those conspiracy fans who still doubt its authenticity please read how I took the photograph."
He then goes on to describe the efforts he went to to get the incredible shot.
"To capture this image I tied myself to the tower of the research boat Lamnidae and leaned into the void, precariously hanging over the ocean while waiting patiently for a white shark to come along.
"I wanted to shoot a photograph that would tell the story of our research efforts to track white sharks using kayaks.
"When the first shark of the day came across our sea kayak it dove to the seabed and inspected it from below. I quickly trained my camera on the dark shadow which slowly transformed from diffuse shape into the sleek outline of a large great white.
"When the shark's dorsal fin broke the surface I thought I had the shot, but hesitated a fraction of a second and was rewarded with marine biologist Trey Snow in the kayak turning around to look behind him.
"I pressed the shutter and the rest was history. Throughout the day I shot many more images, most showing the kayak following the shark, but all lacked the power of that first image of the great white tracking the kayak."
For more images and information and information about his research, grab the book, South Africa's Great White Shark, by Thomas P Peschak and Michael C Scholl.
Back in April, the world's largest great white shark was tagged in Australia. See more on the story in our video below: