A high school senior in Southern California was flying his drone around a beach when he spotted something extraordinary.

A giant whale was swimming toward and then under a group of more than a dozen surfers sitting on their boards in waters near Dana Point, south of Los Angeles, on Monday.

"It was completely surreal and so insane," Payton Landaas, 18, who was operating the drone, told NBC News.

The surfers appeared largely oblivious to the massive mammal, not noticing even when the whale was just feet away.

That is, until the sea creature flicked its tail, sending one surfer swimming away. Others remained in place, seemingly unfazed.

Landaas said that he uses his drone to film around the ocean often, capturing images of everything from dolphins and sharks to seals and sailboats.