Much of the Ocean Cleanup's data on the Great Pacific Garbage Patch comes from a 2015 expedition that involved 18 vessels.
The ships trawled the waters using Manta trawl nets outfitted with mesh to catch as much plastic as possible.
The area they focused on is a particularly concentrated part of one of the five global gyres where ocean currents collect plastic from around the world.
The region itself is huge, at more than 1.6 million square kilometers (617,763 square miles).
In 2016, the Ocean Cleanup conducted an aerial survey of the region to refine its data and count larger pieces of plastic (greater than 50cm) with a Hercules C-130 aircraft.
The Ocean Cleanup is an organization based in the Netherlands, started by young entrepreneur Boyan Slat. The group wants to launch a somewhat controversial effort to clean up the Great Pacific Garbage Patch, and has also conducted research on the scale of the problem.
They collected 1,136,145 pieces of debris that weighed a total of 668 kg and consisted of 99.9% plastic.
From that, the researchers estimated the area has at least 1.8 trillion pieces of plastic in the waters, weighing 79 thousand metric tons — with more arriving every minute of every day.
They estimated that 1.7 trillion of the pieces are microplastics, between .05 and .5 cm in size, but that 92% of the total plastic mass comes from larger pieces.
Shockingly, they also estimated that 46% of the plastic mass is from lost fishing nets known as "ghostnets" that drift through the sea, ensnaring creatures and breaking into smaller bits of plastic.
The team also thinks the 2011 Tohoku tsunami that hit Japan could have significantly added to the mass of plastic.
This may vastly underestimate the amount of plastic in the area, both because they only measured within the boundaries of the "patch" — not the full gyre — and because many other researchers think there are far more microplastics deeper in the water.
While the Ocean Cleanup wants to push for a plan to clean up the plastic in the patch, many researchers think our best bet is stopping pollution from making it into the ocean in the first place.
