Scientists have estimated that there could be 1000 tonnes of plastic washed up on the remote coral atoll of Aldabra.
The island, known as the “Galapagos of the Indian Ocean” because of the sheer variety of life, is more than 400 miles (644 km) from the nearest significant human settlement.
But its position in the ocean currents mean that every high tide brings more plastic.
Access to the atoll, part of the Seychelles, is strictly controlled for reasons of biosecurity but Sky News was allowed ashore to see the threat the plastic poses to wildlife.
We saw turtles crawling over plastic bottles and other debris to lay their eggs in the sand.
Cheryl Sanchez, the science coordinator at the island’s research station, said: “They are very strong. They have to push it aside, which they can do. But it depends on how much it has built up and you have to think about those hatchlings coming out as well.
“They are much smaller and have to crawl through all of this.”
They have bounced back from near extinction, with a population now around 150,000, but plastic is a new threat.
They find it irresistible, particularly yellow and red, possibly because they mistake it for fruit.
Jessica Moumou, a researcher with the Seychelles Islands Foundation, said: “They will eat fragments, and sometimes flipflops, bottlecaps and toothbrushes.
“You pull the plastic and grab it, but they won’t let it go.”
A joint team from the foundation and The Queen’s College, University of Oxford, is now cleaning up the south coast of Aldabra.
They have so far removed 22 tonnes of plastic.
Plastic fishing ropes and nets make up most of the debris by weight, but bottles, cigarette lighters and particularly flip-flops are also common.
Jeremy Raguain, one of the organisers of The Aldabra Clean-up Project, said he expects the team will collect at least 50,000-60,000 flip-flops.
“They are quite durable,” he said. “The currents can bring them over long distances.
“That our trash ends up here is just wrong.
“Aldabra is an amazing protected area, but you have limits on how much you can protect it, whether it is climate change or plastic pollution.
“It is showing you can be a million miles away and you can still have an impact on this place.”
Scientists are concerned that the plastic could bring with it invasive species.
Lindsay Turnbull, from The Queen’s College Oxford, and a trustee of SIF, showed us a foam shoe that had been in the water for so long it had been encrusted with large barnacles.
“(The plastic) is bringing something here,” she said.
“We have on Aldabra an invasive marine sponge that used to be found just on the island of Guam. Gradually it has spread across the Indian Ocean.
“It is known as a coral killer. We don’t want it here.”