Dramatic footage shows a SeaWorld trainer being dragged underwater by two large killer whales.
Tamarie Tollison let out a "blood-curdling" scream as one of a pair of 6,000lb (2,721kg) orcas - named Orkid and Splash - pounced in front of onlookers.
The 28-year-old can be seen on the edge of the tank with her foot dangling in the water at the famous waterpark in San Diego, California.
Suddenly one of the whales grabs her foot as she desperately tries to cling to the tank gate.
Describing the video in documentary Blackfish, former trainer John Hargrove: "At this point Tamarie knows she’s in trouble.
"She’s under the water, Splash and Orkid both have her, she’s totally out of view, no other trainer knows that this is happening.
“People start to scream. You hear Tamarie just scream out ‘somebody help me’ and the way she screamed it was just blood curdling.
"She knew she was going to die."
John went on to explain that quick-thinking fellow trainer Robin Sheets then released the gate of a pool holding another orca, Kasatka.
The much larger female whale was "more dominant" than Orkid and so he let Tamarie go.
She suffered a compound fracture to her arm and was lucky to survive the incident in 2001.
The 2013 documentary film was directed by Gabriela Cowperthwaite and explores the controversy over captive orcas.
Three years earlier SeaWorld had banned trainers from swimming alongside the killer whales.
And despite what is shown in the film, it has always insisted the mammals receive world class care and are non-aggressive, in part thanks to daily "positive reinforcement" training by care specialists.
An accident report from the State of California details how Orkid had also pulled another trainer by the ankle to the bottom of the pool and held him there for nearly 30 seconds in 2006.
In 1991, Tilikum, who weighed 12,500lbs (5,700kg), dragged marine biology student Keltie Byrne under the surface along with his two tankmates after the worker fell in.
A decade later, the large whale killed trainer Dawn Brancheau.
He pulled her into the water by her ponytail at the end of a show as guests were quickly ushered out by staff.
The 40-year-old was scalped and had her arm bitten off.
In another incident in 1987, trainer Joanne Webber, 26, was pushed to the bottom of the 40ft pool when orca Kandu 5 landed on top of her during a practice session.
She suffered a fractured neck.
In a statement sent to the Sun, Seaworld said of the incident involving Tamarie: "That situation happened more than 20 years ago.
"We have extensive protocols and training in place to protect the safety of our trainers and animals.
"This trainer was not following safety protocols in place at the time.
"It is also important to note that trainers have not been in the water training with killer whales for many years."
