It is extremely rare to see a blue whale, a nearly extinct species that is the largest mammal still in existence.

That was the backdrop for a BBC One reporter's trip on a whale watching boat in Monterey Bay in California. 

Steve Backshall was in the middle of an interview with a whale expert when he received word in his ear that the news helicopter had spotted a blue whale near the surface.

Backshall quickly interrupted Dorris Welch, telling her "I don't believe what I've just heard."

"The largest animal ever known to have lived on our planet. Larger than the dinosaurs. It’s back. It’s here. It’s in the bay right now live. This is one of the most extraordinary things I’ve ever seen.”

Backshall was doing a promotional interview for Big Blue Live, airing on PBS and BBC. 

He explained that some blue whales are as long as a jetliner. 

Backshall said when he started out 16 years ago, he never would have dreamed that this moment could be possible. He pointed out that this video shows the "extraordinary comeback" that some endangered species are making thanks to protection efforts.

Watch the rare moment below.

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