Attempts to measure and interpret the distribution and abundance of floating plastics in the surface ocean need to be placed in the context of this natural variability. Plastics occur in all five compartments, and there will be processes acting both within and between compartments which will affect the fate and distribution of the plastic material. Plastics that are inherently buoyant (e.g. PE) can be expected to remain in the upper ocean, unless there is a change in density, for example by the attachment and growth of sessile organisms.