This study presents a Public Participation Geographic Information System (PPGIS) method for spatially identifying and assessing multiple elements of environmental justice in urban blue space. We used this method in the Helsinki Metropolitan Area, Finland, to examine: (1) the diversity and spatial distribution of clusters based on the activities undertaken in urban blue space; (2) the diversity of users in each cluster, representing a composite measure of income, age and family income, and, (3) the extent of perceived problems and unpleasant experiences (PPUE) in each cluster. Proportionately more high activity and high user diversity areas were found in Helsinki than Espoo and Vantaa municipalities. Contrasting combinations of activity and user diversity (high-low, low-high) show very different spatial distributions, dominant activities and PPUE. The method enables landscape and urban planning strategies to be tailored to different types of activities and users, and to be responsive to the PPUE found in urban blue spaces. We encourage future landscape and urban planning research to further develop and apply this PPGIS method for assessing multiple elements of environmental justice.