In an area of Hawaii, far removed from most human habitation, a recent cleanup effort yielded an 18-wheeler’s worth of human debris during a 19-day anti-pollution campaign this year.

The region, which includes Midway Atoll, some 1,200 miles (1,900 kilometers) from the Hawaiian mainland, acts as a “fine-tooth comb” in picking up debris from elsewhere, officials with the National Oceanic and Atmospheric Administration (NOAA) told LiveScience. Broken fishing gear, tattered nets and plastic fragments litter the water and land on the beaches.

As challenging as it is to clean up that much debris, it’s even more of an undertaking to remove it. Heavy machinery could damage the environment, so about 90 percent of the underwater cleanup is done by divers, said Kyle Koyanagi, NOAA’s marine debris operations manager.