(CNN) -- I remember fragments of the story of SeaWorld trainer Dawn Brancheau's killing in 2010 -- something about a ponytail, something about her slipping and falling, something about how this almost never ever happens because in these parks, the animals are happy and the trainers are safe.
But something wasn't right. I remember asking someone why an orca -- a highly intelligent animal -- would attack its trainer or essentially "bite the hand that feeds it."
We sometimes hear of dogs mauling other people, but in these cases we don't seem to hear about them attacking their masters. So why would America's lovable Shamu turn against us? How could our entire collective childhood memories of this delightful water park be so morbidly wrong?
I came in with these questions. I set out to understand this incident, not as an animal activist -- because I'm not one -- but as a mother who had just taken her kids to SeaWorld, and of course as a documentary filmmaker who unfortunately can't let sleeping dogs lie.
I brought Manny Oteyza aboard as the film's producer, and he soon became my right arm. I spoke to Tim Zimmermann who wrote a phenomenal article for Outside magazine about killer whales and asked him to come aboard as an associate producer. I wrote a treatment. We were then funded by investors who had never made a film before. Together we set out to tell this story of an incident at SeaWorld.
I knew immediately that I wanted SeaWorld to have a voice in the film. We e-mailed back and forth for about six months. I gave them every chance to talk, but they eventually declined. At that point, however, I had already began peeling back the onion. And my journey of shock and discovery was well underway.
I have made television documentaries for 15 years, but "Blackfish" is my second feature documentary and my first one to have found theatrical distribution. I can't say this was an easy film to make. There were nightmares, too many autopsy reports, sobbing interviewees and unhappy animals.
And I was scared. SeaWorld is a $2 billion a year entity, and they'll do anything to protect their greatest asset: Shamu. But as I moved forward I knew that in telling this story in an honest and fact-driven way, I was telling the truth. It sounds cliché but it's really that simple. At some point you're simply compelled, in spite of yourself, to tell a story that needs to be told no matter how scared you are of an entity that could squash you.
Two years after I wrote the treatment in 2010 we finished "Blackfish." I can say that my crew and I are all profoundly changed by the experience. I know that killer whales are not suitable for captivity. I am dedicated to spreading the word. The early deaths, the grieving, the boredom, the daily fighting and the attacks -- what we learned over two years is impossible to shake. Once you see it, you can't unsee it.
My hope is that we take the "Blackfish" momentum and use it to help evolve us out of animals for entertainment. These silly marine park tricks are of no social, educational or conservational value. We advocate, instead, for captive killer whales to be retired into sea sanctuaries where they can live out the rest of their lives in a dignified, sustainable manner.
We can't throw them back into the ocean because they don't know how to hunt, their teeth are broken from years of stress and biting on metal gates, and they're hopped up on antibiotics and might die in the open ocean. However, in a sea sanctuary, where a large ocean cove is cordoned off with a net, we could monitor their health, even feed them if need be. It is the best alternative.
People always wonder whether I believe SeaWorld should be closed down. I always say no. They have tremendous financial resources and could play a key role in creating sea sanctuaries which could be a profit-making endeavor. I believe people would flock to a site where a killer whale is being a killer whale for the first time -- something infinitely more satisfying than seeing a killer whale dance the Macarena.
I hope you like the film. I don't know if it will change the way you feel about animals in entertainment parks. I didn't intend for it to do so. I just wanted to tell the real story. And I trust that once audiences are armed with the truth, they will make the best decisions by themselves and their families.
The opinions expressed in this commentary are solely those of Gabriela Cowperthwaite.