The workshop series on sediment dynamics of muddy coasts and estuaries focuses on international frontier issues and major social needs, such as land-sea interactions, estuarine and coastal monitoring, numerical simulation, sediment transport and its biogeochemical effects. The Third Workshop was held in Qingdao, China, in November 2018, hosted by the Institute of Estuarine and Coastal Studies, Ocean University of China. As a result of the Third Workshop, this special issue contains 18 papers with case studies of muddy coasts in the Bohai, Yellow and East China Seas in China and other regions worldwide. These papers represent the most recent advances in Chinese and international estuarine and coastal sediment research in the topics including 1) In-situ observations of sediment dynamics in muddy coasts and estuaries and satellite remote sensing; 2) Modelling of sediment transport and associated sedimentary processes; 3) Fluid mud transport and process in bottom boundary layer, and 4) Blue bay remediation action plan and coastal restoration.