Blue Planet II’s latest episode focuses on how plastic is having a devastating effect on the ocean and slowly poisoning our sea creatures.

Episode four of the acclaimed documentary series, Big Blue, presented by Sir David Attenborough, features a heart-wrenching segment on a hawksbill turtle tangled in a plastic sack, before being freed by a camera operator.

It also details how plastic pollution is killing whales through chemical contamination, showing a pod of pilot whales being emotionally affected by the death of a newborn calf.

“Surviving in the open ocean has always tested animals to their limit, but today they face a new additional threat. Plastic,” says the broadcaster.

The show’s producers revealed to BBC Newsbeat the extent of the plastic problem they witnessed while filming the series.