We apply for an international and interdisciplinary research cruise in the Pacific Ocean to characterize the fate and effects of field-aged microplastic particles and related plastic material. Specifically, we address the identification and characterization of plastic particles, their weathering and fragmentation, sorption and leaching of chemicals to/from plastic material, as well as their incorporation into aggregates and biofilm growth on the particle surface. Our research will provide a major contribution to the current understanding of the transport and fate of microplastic particles in the marine environment, and crucial insights to the great mismatch of the amount of plastic being emitted and that found in surface waters.