Looming from the depths, this huge creature looks as if it is about to swallow diver Sam Bester whole.
Luckily for her, it is actually a whale shark, which only eats plankton.
The picture was taken by Miss Bester's friend Fiona Ayerst off the coast of Durban in South Africa. The diver had been completely oblivious to the shark's presence until Miss Bester pointed it out.
Whale sharks are the largest living fish species and can grow up to 65ft (20m) in length. Some experts believe they can live to the age of 100.
They are found in tropical and warm seas, typically with temperatures ranging between 18 and 30C.
And though the gaping mouth may look terrifying, it has a very practical purpose.
Whales sharks are able to gobble up huge amounts of plankton, sieving out the water swallowed with each mouthful through the gills.
Although they are so big, they are one of the world's more elusive creatures and little is known about them.
Marine scientists dubbed them whale sharks because of their size. They have the skeleton of a shark and are therefore fish, not mammals.
As stunts go, baiting a Great White Shark to take you for a ride by towing your surfboard is an adrenalin rush unlikely to be matched again.
A video purporting to show just this has swept around the world via email in the last few days.
But there's just one small problem - does the footage show a foolhardy daredevil or is it a hoax?
Photographer Kem McNair claims he captured the hair-raising moment on home video from the shore at Florida's New Smyrna beach.
He said the stunt - dubbed 'shark-riding' - has become the latest, and most dangerous, extreme sports craze in more than a decade.
In his video, a 25-year-old male surfer is filmed being dragged along by a fishing line after baiting a shark with chunks of bloodied steak.
Clutching a fishing rod with meat on the hook, the clip begins with the surfer jumping off a pier into the sea. He casts his bait into the water and watches as a 4ft dorsal fin appears on the horizon and heads straight for the line.
After chomping on the bait the shark swims off with the surfer being dragged behind on his board, clutching the fishing line with both hands like a water-skier.
He reaches speeds of approximately 30mph as he races past stunned onlookers enjoying a dip in the sea. After 30 seconds the line snaps and the shark disappears back into the abyss.
Mr McNair insists that what he captured on film has not been faked.
He said: 'I just happened to be panning the camera across the bay when I spotted this dude paddling around with a fishing rod.
'It was so bizarre I had to keep watching watching and it was just a fluke that I captured what happened next.
'He was surfing the breaks as a shark towed him along. The guy must be totally suicidal but it was rad to watch.
'I know a shark when I see one - and this was no hoax. I've got friends who can call any doubters up and set them straight.'
Great Whites are common in waters off Florida. While they usually remain in deep water, Great Whites often venture closer to shore - especially when attracted by floating chunks of meat.
When businessman Daniel Hurst claimed he saw a surfing kangaroo being attacked by a great white shark many people asked whether he had been drinking or was suffering from hallucinations.But 32-year-old Mr Hurst insisted that he had seen the kangaroo bound out from bushes near the beach at Torquay, Victoria, jump into the sea – and then fall victim to a huge shark which leaped up and grabbed it.But the critics were silenced when other proof emerged that he was right.First, a second witness came forward to support Mr Hurst's claim. Then local council authorities confirmed that they had found the mangled carcass of a kangaroo on the beach and had buried it.Finally there was confirmation that kangaroos do like to go for a swim if they get the chance, when a fisherman produced a snap taken recently of one enjoying a bathe in a nearby river.When Mr Hurst told of the shark attack, local newspapers asked for other witnesses – and yesterday Mick Boucher, who had been riding a surfboard at the time, came forward to say he also saw the incident.He watched in astonishment as the kangaroo hopped down the beach and entered the water.
"It was about 200m from shore when the shark struck. I could see its back clearly visible above the choppy waves as it attacked the roo," he said.The local coastal committee confirmed that workers had removed a dead kangaroo found on the beach the day after the attack and had buried it deep in the ground above the high tide mark.To support the claim that kangaroos swim, John Winkler sent in a picture to his local paper showing a roo enjoying an afternoon in the water at the mouth of the Aire River, a few miles from where the other unfortunate animal was grabbed by the shark."I was out on my kayak when I had to look twice because there was this kangaroo swimming along not far from me," he said."It was quite capable in the water, perhaps a little on the slow side, but it wasn't impressed by my appearance."Luckily I was able to take a picture to prove that roos do like to take a dip."
The diver had been completely oblivious to the shark's presence until Miss Bester pointed it out.
