The Great Pacific Garbage Patch is an urban myth, at least the way most people understand it:
"The NOAA Marine Debris Program's Carey Morishige takes down two myths floating around with the rest of the debris about the garbage patches in a recent post on the Marine Debris Blog:
1. There is no "garbage patch," a name which conjures images of a floating landfill in the middle of the ocean, with miles of bobbing plastic bottles and rogue yogurt cups. Morishige explains this misnomer: While it's true that these areas have a higher concentration of plastic than other parts of the ocean, much of the debris found in these areas are small bits of plastic (microplastics) that are suspended throughout the water column. A comparison I like to use is that the debris is more like flecks of pepper floating throughout a bowl of soup, rather than a skim of fat that accumulates (or sits) on the surface.
2. There are many "garbage patches," and by that, we mean that trash congregates to various degrees in numerous parts of the Pacific and the rest of the ocean. These natural gathering points appear where rotating currents, winds, and other ocean features converge to accumulate marine debris, as well as plankton, seaweed, and other sea life. (Find out more about these "convergence zones" in the ocean and a NOAA study of the North Pacific Subtropical Convergence Zone [PDF].)"