This conference report summarizes the current challenges of researching microplastics pollution in the ocean as debated by international experts and stakeholders at a workshop held in San Sebastián, Spain, 1–2 October 2019. The transdisciplinary, co-learning approach of this report stressed the need to incorporate multiple perspective in solving the problem of microplastics and resulted in three proposed actions: (i) filtering microplastics from waste waters; (ii) mandatory ecolabels on plastic products packages; and (iii) circular economy of packaging plastics.