These observations have led scientists to investigate whether humpbacks sometimes respond to distress signals or simply react strongly to the presence of potential threats.
One hypothesis is that the whales possess a powerful defensive response.
A humpback whale may approach a predator and use its enormous body, tail or pectoral fins to disrupt an attack.
Such behavior could be particularly important when protecting calves or other members of its species.
However, an intriguing question remains.
Why might a whale display similar behavior when the animal apparently being protected is not another whale?
One possibility is that the whale was responding to the shark rather than consciously identifying Nan as an individual in need of rescue.
Another possibility is that the animal was exhibiting a broader defensive response that happened to benefit the human nearby.
Scientists cannot determine the whale's exact motivation simply from the footage or the outcome of the encounter.
Nevertheless, the apparent protective behavior is extraordinary.
And for Nan, the experience was deeply personal.
THE OCEAN KEPT ITS SECRET FOR AN ENTIRE YEAR
After the encounter, life continued.
Nan returned to her work, but the memory of the humpback whale remained vivid.
She had spent only a short time with the animal, yet the encounter had created an emotional connection that was difficult to describe.
She remembered its enormous body.
She remembered the way it had repeatedly positioned itself between her and the shark.
She remembered being lifted out of the water.
And she remembered the moment it finally swam away.
But there was something she did not know.
Would she ever see that whale again?
The ocean is enormous.
Humpback whales travel long distances during their migrations, moving between feeding grounds in colder waters and breeding areas in warmer tropical regions.
An individual whale may travel thousands of kilometers throughout a migration cycle.
Even experienced researchers cannot predict exactly where every whale will appear.
Identifying individual whales is possible in many cases because of the distinctive patterns on the underside of their tails, scars, pigmentation and other physical characteristics.
These markings can function almost like fingerprints.
Still, recognizing a particular whale after a long separation is not always easy.
Nan had no guarantee that she would encounter the animal again.
Perhaps it would return to the region.
Perhaps it would pass through another part of the Pacific.
Perhaps she would never see it again.
For almost a year, the memory remained just that: a memory of an extraordinary day beneath the ocean.
Then came an unexpected phone call.
AN UNEXPECTED CALL: THE WHALES ARE BACK!
Almost exactly one year after the original encounter, Nan reportedly received a call from a local fisherman.
The message was simple.
Whales had appeared in the harbor.
For someone who had devoted her life to studying marine mammals, this was already exciting news.
But something about the timing made the moment particularly meaningful.
Could one of those whales be the same animal she had encountered the previous year?
Nan did not wait long.
She quickly made her way to a boat and headed toward the harbor.
As the boat approached the area, the familiar signs of whale activity became visible.
Large bodies moved beneath the surface.
Water disturbed around the animals as they surfaced to breathe.
Their enormous backs appeared briefly before disappearing again.
For a marine biologist, such a sight is always remarkable.
But Nan was searching for something more specific.
She wanted to know whether the whale from the previous year might be among them.
The boat moved closer.
Several people were present.
The whales continued swimming through the harbor.
Then something unusual happened.
One of the animals began approaching the boat.
It did not appear to be moving randomly through the area.
According to Nan's account, the whale came directly toward her.
It seemed to pay particular attention to her presence.
The moment was already emotional.
But the next detail would make the encounter unforgettable.
THE SCARS THAT BROUGHT BACK A TERRIFYING MEMORY
As the whale approached, Nan began studying its appearance.
She looked at its enormous head.
She examined the markings and scars.
And then she recognized something familiar.
The scars appeared to match those of the humpback whale involved in the encounter a year earlier.
For Nan, this was an extraordinary moment.
The ocean had brought her back into contact with an animal she believed had once helped save her life.
Could it really be the same whale?
Individual humpback whales can be identified through distinctive physical characteristics, especially their tail markings and other recognizable features.
Scars can also provide useful clues, although identification is strongest when multiple distinctive features are compared through photographs and research records.
Nan believed she had recognized the animal.
And according to her account, she felt an immediate emotional connection.
The whale was close.
It was moving calmly.
There was no sign of the frantic activity that had characterized their first encounter.
Instead, the moment seemed almost peaceful.
The giant animal remained near the boat.
Nan watched it, overwhelmed by the possibility that she was looking at the same creature again.
A year earlier, she had been frightened by its enormous strength.
Now she was eager to enter the water.
She wanted to see it more closely.
She wanted to be near it again.
And she wanted to experience the extraordinary connection she believed they had shared.
SHE ENTERED THE WATER — AND THE WHALE APPROACHED AGAIN
Nan eventually slipped into the water.
The moment was completely different from their first encounter.
There was no immediate sense of danger.
No sudden struggle.
No shark visibly circling behind the whale.
Just the vast blue water and the enormous animal moving nearby.
The whale approached her.
It came close enough for her to observe its face and body.
For a few moments, Nan and the whale appeared to remain near each other.
The animal reportedly looked directly toward her.
Then came one of the most emotional details in her account.
The whale gently extended its massive pectoral fin.
Nan described being able to rest against it and embrace the animal.
Think about the contrast.
The same kind of enormous fin that had lifted her out of the water during a terrifying encounter was now part of a seemingly gentle interaction.
The whale moved close to her.