Alright, let’s see how well you do on this quick test. Can you guess which sample came from the North Pacific Garbage Patch and which came from the South Pacific Ocean? Pretty obvious, isn’t it?

I juxtaposed these photos so you could see the difference between a water sample from inside a gyre (right) and a sample from the open ocean (left)*. A gyre, a whirlpool-like collection of swirling currents, can concentrate an enormous amount of debris and scientists from organizations like NOAA, Scripps Institution of Oceanography, the Algalita Marine Research Foundation and 5 Gyres are still trying to figure out if there’s twice as much plastic in a gyre, five times as much or even more.

Captain Charles Moore, who’s become the unofficial spokesperson for the North Pacific Garbage Patch, famously sampled an area between California and Hawaii where he found six times as much plastic as plankton by weight during the late 1990s.

And Nikolai Maximenko, a senior researcher at the International Pacific Research Center at the University of Hawaii, Honolulu, has produced a graphic showing where garbage collects in the ocean. His model has allowed scientists to pinpoint exact locations to sample and some of these samples have made their way around the world as educational groups like Algalita and 5 Gyres give samples to schools and community groups.

So that’s the post for today; I have to sign off because we’re almost in Rarotonga! We’ve picked up speed and should arrive in the next 15 hours. Once we’re in the Cook Islands we’ll be looking at bleached coral and sulfur and nitrate levels in lagoons located near pig farms and septic tanks. More to come soon!

*What’s even more astonishing about these photos is that the sample on the left is the result of a seven-hour trawl and the sample on the right is from an hour-long trawl!

Image credits: Photos 1 and 2: Lindsey Hoshaw; Image 3: graphic by Nikolai Maximenko

About the Author: Lindsey Hoshaw is a freelance environmental journalist. Her work has appeared in The New York Times, the Boston Globe and Forbes, among others. In her spare time she moonlights as a garbologist studying people and the things they throw away. Follow her on Twitter @thegarbagegirl.

Editor’s note: The South Pacific Islands Survey is part of a larger multiyear expedition run by Pangaea Exploration, a nonprofit that investigates the health of marine life through exploration, conservation and educational outreach. The expedition focuses on marine debris, water quality, habitat conditions and overfishing in the world’s oceans. Specific emphasis is placed on the five gyres, or the five areas with the highest accumulation of plastic pollution.

The views expressed are those of the author and are not necessarily those of Scientific American.