The moment a 25-ton humpback whale pushed a snorkeller to safety from a 15ft tiger shark was captured on camera.
Biologist Nan Hauser was swimming off the coast of Rarotonga, in the Cook Islands, when the giant creature swam-in to prevent a "potentially deadly" attack.
She said the encounter may be proof of a whale's intuitive nature to protect other species, including humans.
She believes this has never been captured on video before and could be the first ever documented case of a humpback whale guarding a human from a shark.
The giant whale tucked the 63-year-old, under its pectoral fin and pushed her along with his head and mouth for around 10 minutes, she said.
She later realised that the 15-foot tiger shark was nearby, that the whale was steering her away from. She had initially thought it was another whale until she realised it was moving its tail from side to side rather than up and down, she said.
“I’ve spent the past 28 years protecting whales, and in the moment, I didn’t even realise that they were protecting me," she added.
She likened the whale’s altruistic actions to those of a firefighter, rushing to save people they don’t know from a burning building. In almost three decades of studying whales, Ms Hauser she said she had never witnessed such behaviour.
But despite the display of what she believed was altruism, the biologist said she feared for her life and thought it could end up as a “deadly encounter”.
“I wasn’t sure what the whale was up to when he approached me, and it didn’t stop pushing me around for over 10 minutes. It seemed like hours. I was a bit bruised up,” she said.
“I’ve spent 28 years underwater with whales, and have never had a whale so tactile and so insistent on putting me on his head, or belly, or back, or, most of all, trying to tuck me under his huge pectoral fin.
“I tried to get away from him for fear that if he rammed me too hard, or hit me with his flippers or tail, that would break my bones and rupture my organs. If he held me under his pectoral fin, I would have drowned.”
She added: “I didn’t want to panic, because I knew that he would pick up on my fear. I stayed calm to a point but was sure that it was most likely going to be a deadly encounter.”
A second whale was also trying to keep the shark away from her by slapping its tail, she said.
While she did not notice the shark at first as her attention was firmly on the "tactile" whale, she said: “Other fishermen and divers have seen this same shark nearby the reef and say that it is as big as a pickup truck. Some say that it is 20 feet long."
The diver’s team, who were in a nearby vessel, also feared for her safety and abandoned their drone footage because, they "did not want to film my death," Ms Hauser said.
She had heard of the altruistic behaviour of humpback whales before - protecting their young, other species of whales, seals, and dolphins - but scientists have never seen humpbacks actually protecting humans. However, such actions have been previously witnessed in dolphins.
The biologist now hopes to share the footage she and her team were able to capture, in order to expand research and awareness of such actions from whales.
Ms Hauser said: "There is a published scientific paper about humpbacks protecting other species of animals, by Robert Pitman. For instance, they hide seals under their pectoral fins to protect them from killer whales. They truly display altruism - sometimes at the risk of losing their own lives.”
The biologist said she does not encourage touching whales.
"I never touch the whales that I study unless they are sick or stranded on the beach, she said. "In my head, I was a bit amused since I write Rules and Regulations about whale harassment - and here I was being harassed by a whale”.
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