No matter how much a diver plans for it, the sea is never truly your friend. At any moment, danger can be lurking from beneath and nothing can prepare you for everything you might encounter. And when a shark is headed your way, often there is no one around to save you.

But for one marine biologist, she didn’t need a typical hero. Turns out, all she needed was a 50,000-pound humpback whale. Nan Hauser, 69, found herself face-to-face with the giant whale just as a 15-foot tiger shark made its way toward the pair.

A tiger shark was aiming for a diver, when a humpback whale scared off the shark, and helped the diver back to her boat. Photo by National Geographic

Hauser had been diving in the South Pacific Ocean, when the curious whale swam toward her. Something that is common during dives, she said. But, what wasn’t normal is how the whale reacted when they both realized what was below them.

I suddenly realized that the shark is coming up just at me right below,” she said.

Hauser said that immediately the tension ratcheted up, and both she and the whale were aware “that this is a serious situation, and I wanted to get out of the water.” Tiger sharks, she said, are well known for attacking humans. But what the whale did next still has scientists looking for answers, all while Hauser is just grateful.

Captured on video, the whale is seen putting itself between the diver and the incoming shark. Out of shot, the hulking humpback whale was frantically slapping its tail to warn the shark away from Hauser. “All of a sudden, I was swooped up by the whale that had been pushing me and now he’s got me right on the front of his face,” she said.

Nan Hauser indicates she is safe, after a humpback whale guided her away from a tiger shark. Photo by National Geographic

Using its head, the whale gently pushed Hauser toward safety, giving her time to climb aboard her boat. Once she was safe, Hauser said she immediately checked on the whale. “I looked and he was right there next to me, protecting me… And I cried.” The whale then swam away with an acknowledging spray from its blowhole.

Her story is now part of National Geographic’s annual Sharkfest event. Scientists are still researching why a whale would have saved a human. There are multiple theories, but the prevailing one is that the actions toward Hauser were similar to a mother humpback towards its calf. The behavior, they say, is ‘spillover’ from their need to protect their own calves.

In all of her diving experiences, this is the one Hauser said she will always remember. And she is forever in awe of the kindness of a species that could easily overpower a human with a single swipe of its fin. “I still to this day can’t believe it happened and being a scientist it’s even harder,” she said. “If someone told me this story, I wouldn’t believe them.” Watch her amazing encounter, below.

Sources: Daily Mail | The Sun