9 Awesome Movies That Were Shot In Secret

3. The Cove

Louie Psihoyos' Oscar-winning documentary expose of brutal dolphin hunting operations in Japan is a heartbreaking, discomforting call to action for the country to curb the cruelty of its dolphin-herding practices.

In order to capture the grim footage that would truly open the world's eyes to the horror, Psihoyos, himself a former National Geographic photographer, had to disguise their underwater cameras and microphones as rocks, which were so convincing that the film's crew struggled to relocate them after shooting.

The final film features incredibly disturbing glimpses of dolphins being lured into a cove to be efficiently slaughtered en masse, which helped deliver its message with bracing, sledgehammer force. Though some critics called the film out for being one-sided, it was widely praised for bringing national attention to an important issue.