The name “Pacific Garbage Patch” has led many to believe that this area is a large and continuous patch of easily visible marine debris items such as bottles and other litter —akin to a literal island of trash that should be visible with satellite or aerial photographs. While higher concentrations of litter items can be found in this area, along with other debris such as derelict fishing nets, much of the debris is actually small pieces of floating plastic that are not immediately evident to the naked eye.

The debris is continuously mixed by wind and wave action and widely dispersed both over huge surface areas and throughout the top portion of the water column. It is possible to sail through the “garbage patch” area and see very little or no debris on the water’s surface. It is also difficult to estimate the size of these “patches,” because the borders and content constantly change with ocean currents and winds. Regardless of the exact size, mass, and location of the “garbage patch,” manmade debris does not belong in our oceans and waterways and must be addressed.

http://marinedebris.noaa.gov/info/patch.html

MYTH: There is a giant island of solid garbage floating in the Pacific.
FACT: There are millions of small and microscopic pieces of plastic, about .4 pieces per cubic meter, floating over a roughly 5000 square km area of the Pacific. This amount has increased significantly over the past 40 years.

In reality, Goldstein said, most pieces of garbage in the Pacific are "about the size of your pinkie fingernail." Though she and her team have found some larger pieces of plastic, like buoys and tires, most are microscopic. What's alarming about them isn't their size, but the sheer amount of plastic. To figure out how much there really is, she and her team have trawled the surface of the ocean in random locations over a 1700 square mile region in the gyre. Once a day, they drag a very fine, specialized net behind the boat. On one such sampling trip, she and her team found plastic pieces in 117 out of 119 random samples. On another, they found plastic in all 28 samples they took.

Since the 1970s, scientists have been using the same sampling methods — and the same kinds of trawling nets, invented by oceanographer Lanna Cheng — to measure the amount of plastic in the ocean. So Goldstein and her colleagues are able to make historical comparisons, and measure increases in plastic density. In a recent paper, they write, "Microplastic debris in the North Pacific increased by two orders of magnitude between 1972–1987 and 1999–2010 in both numerical and mass concentrations."

http://io9.com/5911969/lies-youve-been-told-about-the-pacific-garbage-patch