The Great Invisible shines light on Gulf of Mexico spill

The cameras have left, but tears continue to fall in the Gulf of Mexico, four years after the environmental catastrophe caused by an explosion on British oil giant BP's Deepwater Horizon rig.

In The Great Invisible, a documentary that won the Grand Jury prize at the South by Southwest festival in Texas, director Margaret Brown shines the spotlight back on the main victims of the disaster.

These include fishermen and oyster farmers whose businesses were devastated by the tide of oil, as well as children from the US states of Louisiana, Texas and Alabama on the front line of the vast slick.