Some 3,000 killer whales spend time in Norway's Barents Sea, but not many of us will ever get an underwater look at them. This stunning clip, captured during a 2016 encounter off the cost of Tromsø, was released by a group of documentary filmmakers who rank among the lucky few.

Spanish diver David Gonzalez Buendia was guided to the pod by sailor and marine biologist Andreas B. Heide, who embarked on a three-week expedition last year to film overwintering whales.

"I was more excited than scared," Buendida told The Local. "I've been diving for many years, but never before with orcas. Once in the water I was amazed at how magnificent these animals are ... gentle and at the same time really powerful."

You'll notice several whales using their powerful tails to herd and stun the silver fish in the video. This tactic is known as slap-hunting, and it's particularly effective in subduing the favourite snack of Norwegian orcas: Atlantic herring.

Fish isn't the only thing on the menu for these giants, however. Researchers recently discovered that a select few also feast on larger prey like seals – and they've even been known to share a mammalian meal with one another.

"Every day was mind-blowing," says Buendia of the experience. 

Freediving with orcas is legal in Norway, but in many countries – like the United States – approaching wild whales is strictly prohibited. We're happy to see that Buendia and the crew refrained from touching or closing in on any members of the pod. Though the only instances of orcas attacking people have taken place at aquatic parks, these animals still rank among the largest predators in the oceans, so any interactions demand caution and respect.

Top header image: Kenai Fjords National Park/Flickr