Shocking moment SeaWorld killer whale drags trainer underwater and holds him there for 15 minutes

Shocking footage shows the moment a killer whale held at SeaWorld dragged its trainer under the water and refused to let go for 15 minutes.

The theme park sparked widespread controversy for keeping orcas captive as part of its attractions for customers, with many activists citing the animals' violent actions as one of the reasons they should not be held in such confined spaces.

One SeaWorld trainer, Dawn Brancheau, lost her life to a killer whale when it attacked her in 2010, but before that another Orca, named Kasatka, became violent with her own trainer.

Footage of the terrifying and drawn-out attack against Ken Peters in 2006 was first released as part of litigation against SeaWorld by the US Secretary of Labor, and it later went on to form part of the 2013 award-winning documentary Blackfish.

In the video, Ken was working with Kasatka in front of a crowd of people when the killer whale suddenly clamped him in its jaws.

As the audience watched on, Kasatka dragged Ken all the way to the bottom of the pool, forcing the trainer to try and hold his breath.

Thankfully Kasatka did bring Ken back up to the surface for a few seconds, allowing him to catch his breath, but the ordeal was far from over.

Ken was dragged around and held underwater by Kasatka for a period of 15 minutes, until he eventually managed to escape her grip.

Ken Peters was forced to hold his breath for a minute amid the attack. (ABC News)

In the book Death at SeaWorld, author David Kirby described Kasatka as having 'rag-dolled' Ken.

He wrote: "When he resurfaced, she grabbed him again, this time 'rag-dolling' her trainer violently by shaking him back and forth with her powerful neck muscles."

In spite of everything he'd just been through, Ken didn't appear afraid of the animal as he patted her on her side and stroked her as he moved slowly away.

He was then pulled out of the water by one of his colleagues.

It was a miracle that Ken survived the ordeal, and afterwards he admitted that he knew of the dangers that came with swimming with a wild animal.

"I could get killed in a car accident today, but I still get in a car," he said.

"Even when I was down at the bottom of the pool, I thought she’d let me go."

When the video was presented at the court hearing, Judge Ken Welsch described the scene as 'chilling'.

Just over a decade after the attack, Kasatka was put down at the age of 41.