This document specifies test methods for the determination of the degree of disintegration of plastic materials immersed to marine habitats under real field conditions. The marine areas under investigation are the sea surface or the coastal area with a depth of 3 m or more. It is a test to evaluate the disintegration of a plastic floating in the coastal area, and the test is performed by submerging the target sample to a depth of 1,5 m or more to reproduce the floating state in seawater. This document specifies the general requirements of the apparatus, and the procedures for using the test methods described. The determination of the degree of disintegration of plastic materials exposed to the sandy sublittoral and the sandy eulittoral zone, where the disintegration depends on their physical characteristics, form and size of the materials, and on water currents and tidal movements, are not within the scope of this document. This document is not suitable for the assessment of disintegration caused by heat or light exposure. The described field test is a bio-disintegration test and not a biodegradation test. Therefore, it cannot be used for demonstrating biodegradation or for making unqualified claims such as “biodegradable in marine environment” and similar.