Microplastics – small bits of plastic millimeters or smaller in size – that float in the ocean are carried by surface currents to oceanographic “dead-ends” known as subtropical ocean gyres. Yet how these particles move vertically in the water column remains poorly understood. We will carry out laboratory experiments designed to inform numerical ocean models that predict where in the water column these microplastics may be found, which may have implications for the marine animals that live there.