Modern technology has brought many benefits, but few more transformative than the ability to easily and cheaply document life. Most people carry a camera in their pocket. Activism has moved from a participatory group event to something easily done online. What every media campaign now needs is that one picture which will capture the public’s imagination. There’s rarely any question as to how that image was obtained.

The pink river dolphin, whose habitat is the Amazon river, has almost been hunted to extinction. This is due to local fishermen using them as bait for a scavenger fish. Marine biologist Dr. Fernando Trujillo and Richard Rasmussen, a biologist and TV presenter, join forces to raise awareness and protect this endangered species. Richard secures footage of dolphins being slaughtered, which is broadcast to millions of viewers on a popular primetime show in Brazil; prompting the government to take action. However, ethical and moral concerns are raised around how these images were captured.

In A River Below, director Mark Grieco has managed to create one of those rare documentaries which start out as one film before morphing into something different. Whilst the threat to the dolphins is palpable, the focus shifts to the villagers and whether they’ve been exploited. To put it mildly, Rasmussen is a personality. He’s eminently watchable, but I’m not sure you’d want to trust him! A River Below is a fascinating documentary on modern activism, ethical filmmaking and the potential cost of protecting an endangered species.

A River Below screens at Sheffield Doc/Fest.