A Maine marine biologist says footage of her swimming with a humpback whale shows the large mammal protecting her from a tiger shark.

Nan Hauser, President of the Center for Cetacean Research and Conservation and a Brunswick resident, says she uploaded footage of her encounter Monday and it quickly spread across the Internet.

Hauser says she was in the Cook Islands when she came face-to-face with a 25-ton humpback whale, which approached her and began nudging her around the water.

She says the whale also shielded her with a fin.

She says after the encounter, she noticed a tiger shark was swimming nearby.

Hauser says whales are "altruistic" but she has never experienced or read about anything like this before.

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