Watch a humpback whale protect a diver from a tiger shark

It can be a literal lifesaver when an authority figure pops up to help you navigate an unfamiliar place. It turns out that humpback whales are down to fill that role in the ocean.

That’s what marine biologist Nan Hauser discovered while diving near the Cook Islands. In a video shared on Monday, Hauser is observing a humpback whale when all of the sudden her massive new sea friend pushes her through the water with his nose. When Hauser tries to move to get out of the way, the 50,000-pound humpback tucks her under his pectoral fins and continues to nudge her away from where they had been swimming. The exhausting (and frightening) experience lasts for ten minutes. Finally Hauser is let go, only to realize that there is 15-foot tiger shark prowling where she and her krill-eating pal had just been swimming together.

Humpback whales have a reputation for altruism, and there have been reports of them protecting dolphins and other sea creatures, but Hauser says that this is the first time a humpback has been filmed trying to protect a human. Hauser is the president of the Center for Cetacean Research and Conservation and has worked to protect whales from harassment and harm by humans for 28 years. It seems like one of her baleen buddies got the message and decided to return the favor.