Ocean garbage patches

Winds and currents transport marine debris across the ocean. Rotating current systems called gyres can concentrate some floating material toward particular regions, often near their centers. NOAA describes five major ocean gyres—one in the Indian Ocean, two in the Atlantic, and two in the Pacific—and notes that garbage patches of varying sizes occur in these systems. Their precise boundaries and dimensions are difficult to fix because debris moves with winds and currents.

The phrase “garbage patch” can suggest a visible island, but a patch is not a continuous raft of rubbish. Debris is dispersed over a large area and may occur at different depths, from the surface toward the seafloor. It includes large objects such as lost fishing nets as well as small plastic fragments and microplastics. Concentrations vary across a patch, and some parts may have little visible debris even while smaller pieces are present.

Marine debris can harm wildlife through entanglement and ingestion; lost fishing nets may continue trapping animals, a process often called ghost fishing. Debris can also carry organisms to new areas and create hazards for vessels. NOAA notes that garbage patches are remote and difficult to study, and that the effects of microplastics on human health remain uncertain. Because tiny pieces are dispersed and mixed through the water, removing all debris from open-ocean patches is difficult. Prevention—reducing debris entering waterways and oceans—and cleanup in accessible coastal areas are important parts of the response.