A video has emerged, showing a seal choking on a plastic bag in the ocean.
Dafydd Thomas shot the video of the suffering sea creature in the waters of Trearddur, a seaside town off the coast of Anglesey, Wales.
"Sad sight this morning, poor seal battling trying to free itself from some plastic in its mouth," he wrote.
The footage, which Mr Thomas recorded in November 2016 but recently reposted to Facebook, shows the seal struggling to free itself from the plastic in its mouth, bobbing in the water a few metres from the shore.
The seal then sinks below the water and is not seen again.
Aberporth in West Wales recently became the first plastic-free village in the country. Restaurants and cafes have stopped using plastic straws and cutlery, and encourage customers to bring their own cups, rather than use disposable ones.
Plastic milk bottles have also been replaced by glass in the village's local convenience store.
Approximately 7.25 million tonnes of plastic are dumped into the ocean every year - the equivalent to 16 shopping bags full of plastic per metre of coastline for every land mass on Earth, excluding Antarctica.
At the current rate, by 2050, it's estimated the ocean will contain more plastic than fish.
The Prince of Wales - Prince Charles - called the issue of ocean pollution a "supreme wake-up call" at the Our Ocean conference in October 2017 and implored people to take better care of the marine environment.