Plastic Bag Found at the Bottom of World's Deepest Ocean Trench

View Images A plastic bag floats through Manila Bay in the Philippines.

Photograph by Randy Olson, National Geographic

The Mariana Trench—the deepest point in the ocean—extends nearly 36,000 feet down in a remote part of the Pacific Ocean. But if you thought the trench could escape the global onslaught of plastics pollution, you would be wrong.

A recent study revealed that a plastic bag, like the kind given away at grocery stores, is now the deepest known piece of plastic trash, found at a depth of 36,000 feet inside the Mariana Trench. Scientists found it by looking through the Deep-Sea Debris Database, a collection of photos and videos taken from 5,010 dives over the past 30 years that was recently made public.

Here's How Much Plastic Trash Is Littering the Earth

Of the classifiable debris logged in the database, plastic was the most prevalent, and plastic bags in particular made up the greatest source of plastic trash. Other debris came from material like rubber, metal, wood, and cloth, and some is yet to be classified.

Most of the plastic—a whopping 89 percent—was the type of plastic that is used once and then thrown away, like a plastic water bottle or disposable utensil.

While the Mariana Trench may seem like a dark, lifeless pit, it hosts more life than you might think. NOAA's Okeanos Explorer vessel searched the region's depths in 2016 and found diverse life-forms, including species like coral, jellyfish, and octopus. The recent study also found that 17 percent of the images of plastic logged in the database showed interactions of some kind with marine life, like animals becoming entangled in the debris.

Where Did the Plastic Come From?

The new study is just one among many showing just how prevalent plastic pollution has become worldwide. Single-use plastics are virtually everywhere, and they may take hundreds of years or more to break down once in the wild.

Last February, a separate study showed that the Mariana Trench has higher levels of overall pollution in certain regions than some of the most polluted rivers in China. The study's authors theorized that the chemical pollutants in the trench may have come in part from the breakdown of plastic in the water column.

Plastic has recently become a greater focus of the environmental movement, being featured prominently this past Earth Day, for example. While plastic can enter the ocean directly, such as trash blown from a beach or discarded from ships, a study published in 2017 found that most of it is flowing into the sea from 10 rivers that run through heavily populated regions.

Discarded fishing gear is also a major source of plastic pollution, and a study published last March found that the material comprised the bulk of the Texas-size Great Pacific Garbage Patch floating between Hawaii and California.