<p>Elevated terrestrial nutrient loads entering coastal waters in northeastern Australia are adversely affecting the Great Barrier Reef World Heritage Area. ‘Seaweed biofilters’ have been proposed as a mechanism for the bioextraction of elevated nutrient levels from coastal environments, with potential to target diffuse source nutrient discharges while generating biomass with potential applications as fertiliser, soil conditioning agents and agricultural fodder. Here, we use a novel modelling approach to identify optimal candidate locations for seaweed biofilter deployment in northeastern Australia’s coastal waters, prioritising sites for more detailed assessment and on-ground feasibility evaluation. The analysis integrates spatial layers representing regulatory constraints and practical deployment considerations with a model for the seaweed growth potential. Growth potential is determined from outputs of the Environmental Modelling System (EMS), a sophisticated environmental model that simulates coupled physical, chemical, and biological processes and is continuously operated over the Great Barrier Reef region as part of the eReefs project. Based on this analysis, fourteen sites, located near river mouths, satisfied the selection criteria and were identified as potential candidates for seaweed biofilter deployment.</p>