Gabriela Cowperthwaite

Documentary filmmaker Gabriela Cowperthwaite on a Los Angeles beach in November 2013. Her film "Blackfish" has changed the way she looks at the world, she says. (Don Bartletti / Los Angeles Times / November 19, 2013)

SAN DIEGO — Gabriela Cowperthwaite looked out the window of a train at the ocean and the bros surfing and the fish taco stands whizzing by.

"I'm antsy," she said, shifting in her seat. She checked her cellphone, which she had largely been ignoring all day. There were a few messages about work prospects, and another from her husband about their 7-year-old twin boys.

Usually, Cowperthwaite drives her sons to their school in Venice. But on this Monday in February, she had been with thousands of other kids, touring middle schools to answer questions about her documentary "Blackfish."

This wasn't where she thought she'd be a year ago, when the film about the plight of killer whales performing at SeaWorld premiered at the 2013 Sundance Film Festival. But "Blackfish" has since become one of the most controversial documentaries to hit theaters in a decade.

High-profile musicians have canceled gigs at SeaWorld, and dozens of celebrities have tweeted about the movie, urging their followers to stop going to the theme park. Animal rights activists turned up at both the Macy's Thanksgiving and Rose parades to protest the company's whale-centric floats.

In December, SeaWorld bought full-page ads in eight newspapers, rejecting allegations of animal mistreatment. Jim Atchison, the company's president and chief executive, insists most park guests "see the story for what it is — an activist agenda."

The experience has engulfed the 43-year-old Colorado native, who had only one feature film under her belt before "Blackfish." She spends her days sitting for interviews or traveling to screen her film. Because her movie was nominated for a handful of prizes, she also braved the awards season gantlet, walking red carpets and attending stuffy rubber chicken dinners.

"I even put on fake lashes today," she said, pointing to her otherwise makeup-free face. An oversized bouquet of flowers she'd received as a gift from a school mom rested on the empty seat beside her, beginning to wilt.

It's what most filmmakers dream of — particularly those who make low-budget documentaries. But devoting all of her energy to "Blackfish" has also left Cowperthwaite unable to move on to new work.

"I've been doing this for over a year now, and have come this far as a steward, which seems to have worked," she said as the train approached Los Angeles. "So I feel a kind of responsibility to keep steering this in the right direction. But just how do you continue to do that when in your heart of hearts you know that you should be moving on to your next film?"

A gangly arm rose above the crowd seated in the auditorium at Monroe Clark, a middle school 15 minutes from SeaWorld.

"Um," the teenage girl began, "How much money did you make from making this movie?"

Cowperthwaite smiled tellingly, pausing before she answered.

"Wait," the girl said, "are you saying you didn't make any money?"

"Zero," the filmmaker responded.

"Say whaaaaa?" one boy yelled, causing a teacher to rush over to reprimand him as the rest of the room erupted into applause.

By her own admission, Cowperthwaite isn't a "business-minded shark." But she's no idiot, either.

While working toward a PhD in political science at USC more than a decade ago, she took a documentary class and was hooked. So she started interning at a company that made documentary-style programming for the Discovery Channel and National Geographic. Soon, she was directing a series about the Iraq war for the History Channel, and went on to create an independent documentary, "City Lax," about inner-city kids who play lacrosse, that she sold to ESPN.

She started thinking about making a film on SeaWorld after taking her sons there. They sat in the splash zone, where they were sprayed with water by an orca's massive tail. Cowperthwaite was floored by the beauty of the whales' speed and strength, but when a trainer stood on one of the animal's backs, she cringed.

"There's something about it that felt wrong, but I couldn't figure out what it was, exactly," she recalled. "There's so much glitz and you're subjected to thumping music and bright colors and smiling people, so you become kind of anesthetized."