Henderson Island: One of the most polluted places on Earth

Welcome to Henderson Island, a remote outcrop in the South Pacific Ocean.

It's home to 55 species found nowhere else on Earth and it also has the unenviable title of most polluted place on the planet.

The island, around 5500km east of Auckland, is part of the UK's Pitcairn Island territory and is so isolated it's only visited once or twice a decade for research purposes.

No humans live there, but there are obvious traces of them with a new study showing the island's once pristine beaches have 671 pieces of debris including plastics per square metre.

Henderson Island (Dr Jennifer Lavers / Supplied)
Henderson Island is far from pristine, despite no humans living there (Dr Jennifer Lavers / Supplied)

It's the highest density ever recorded and has researchers issuing a stark reminder of how the plastic you throw away which ends up in the ocean can land in even the most remote places on Earth.

"What's happened on Henderson Island shows there's no escaping plastic pollution even in the most distant parts of our oceans," Australia's Institute for Marine and Antarctic Studies research and lead author Dr Jennifer Lavers says.

"Far from being the pristine 'deserted island' that people might imagine of such a remote place, Henderson Island is a shocking but typical example of how plastic debris is affecting the environment on a global scale."

Much of the debris which has ended up on the island is believed to have come from South America, around 5500km away, or discarded by fishing vessels.

On the latest expedition to the island, led by Britain's nature conservation charity RPSB, five beach sites were sampled.

The study estimated more than 17 tonnes of plastic debris had made it to land, with more than 3570 new pieces of rubbish washing ashore per day on one beach alone.

But while that sounds like an astronomical amount of trash for an island just 36 square km in size, Dr Lavers says it's likely they've underestimated their figures.

"We were only able to sample pieces bigger than two millimetres down to a depth of 10 centimetres, and we were unable to sample along cliffs and rocky coastline."

Of the more than 300 million tonnes of plastic produced around the world each year, most of it isn't recycled, Dr Lavers says.

The fact plastic floats and doesn't break down quickly or easily means it has a long-term impact on the world's oceans and the wildlife which calls it home.