Plastics pollution is a global environmental and human health issue, with plastics now ubiquitous in the environment and biota. Despite significant international research, key knowledge gaps (“known unknowns”) remain around ecosystem-scale and human health impacts of plastics in the environment, particularly in limnetic, coastal and marine systems. Here, as part of the multi-national TRANSPLAS project, we: (a) review aquatic plastics research and data in three contrasting geographic and cultural settings, which present a gradient of heavily urbanised to more pristine environments: China, the United Kingdom, and Australia; and (b) present data from standardised fieldwork which compares, using standard methods, plastics pollution in various coastal settings in the southern UK, southwestern Australia and eastern China. To date, development pressures and necessary responses in each nation have defined the skills developed and their research foci, and there is a bias in national research priorities driven by levels of pollution, funding, government priorities and academic areas of interest. This has resulted in aquatic plastics datasets that are hard to compare directly, supporting the need to converge on standardised sampling methods, and bioindicator species. Standardisation is critical to make geographic comparisons more reliable, and here we present initial results from simultaneous field deployments and training programmes in Australia, the UK and China, using standard methods to provide comparable aquatic plastics data between each coastal setting.