90% of the garbage floating in the Earth’s oceans is plastic and less than 5% of all plastic is recycled. The patch mostly consists of pelagic plastics, formed from plastic bags, plastic water bottles, bottle caps and styrofoam. Plastic does not biodegrade, the sun breaks these down into smaller and smaller pieces through photodegradation, which is why it is so difficult to judge the size of the patches, since these pieces are not visible from satellites or planes.
Debris ranges in size from abandoned fishing nets to micro-pellets found in abrasive cleaners. Garbage from Asia’s east coast takes about a year or less to enter the Pacific gyre, while trash from the west coast of North America can take up to 6 years.