This European Standard gives guidelines for characterizing the hydromorphology of transitional or coastal (TraC) waters, but does not prescribe detailed methods of assessment. The main aim of this document is to improve the comparability of hydromorphological survey methods, data processing, and the interpretation and presentation of results. This European Standard: a) lists essential features and processes of TraC waters that should be characterized as part of a hydromorphological survey and used for determining hydromorphological condition; b) gives guidance on strategies for collecting and presenting hydromorphological data depending on the resources available and the anticipated use of the assessment; c) describes how to generate data sets appropriate for monitoring and reporting on the condition of Natura 2000 sites designated under the Habitats Directive and the Birds Directive; d) provides guidance on data quality assurance. This European Standard does not deal with biological assessments in TraC waters such as the presence or absence of individual species or community composition, nor does it attempt to link specific hydromorphological features with their associated biological communities. However, it is relevant where plants or other organisms form significant structural elements of the habitat (e.g. saltmarshes, biogenic reefs).