maintain Good Environmental Status (GES), including underwater noise as one of of the eleven speci?c criteria for evaluating GES. In 2022, the EU established quantitative threshold values for addressing the consequences of impulsive underwater noise input into the marine environment. In this chapter, a data- driven stepwise approach is introduced for the implementation of an MSFD compatible assessment methodology. Corresponding standardized practices are presented. For the data-driven evaluation of regional requirements and of the applicability of harmonized methodologies within EU regions, exemplary regional case studies were performed for the Baltic Sea, North Sea, and Mediter- ranean Sea. Further, the estimation of effect ranges and corresponding risks of adverse effects is important for an impulsive noise assessment. Regional differ- ences in the marine environment were addressed. Main challenges of impulsive noise propagation modelling were identi?ed based on both numerical and ana- lytical/empirical propagation modelling. Finally, recommendations for the impul- sive noise registries are presented. Keywords Impulsive underwater noise · Regional assessment · Noise registries Introduction The EU Marine Strategy Framework Directive (MSFD) (Directive 2008/56/EC) provides an important framework for a sustainable use of the seas within the European Union, which explicitly includes the effects of underwater noise in an assessment of the state of the marine environment. The MSFD was adopted to protect the marine ecosystem and biodiversity and obliges EU member states to achieve and maintain Good Environmental Status (GES). Descriptor 11, underwater noise, is one of the eleven speci?c descriptors for Good Environmental Status. Descriptor 11 (D11) comprises two criteria, with the ?rst criterion (C1) relating to Anthropogenic impulsive sound in water (Commission Decision 2010/477/EU). In 2022, the EU introduced MSFD-related quantitative threshold values for underwater noise, including impulsive noise (D11C1), for the ?rst time. The focus of these thresholds is on the protection of habitats of noise-sensitive marine species. Commission Decision (EU) 2010/477/EU provides relevant criteria and method- ological standards for the Descriptors of GES. For the assessment of GES in relation to D11, the temporal and spatial distribution of impulsive underwater noise (loud, low and mid frequency impulsive sounds) was identi?ed as a primary criterion (D11C1). It is speci?ed as proportion of days and their distribution within a calendar year over areas of a determined surface, as well as their spatial distribu- tion, in which anthropogenic sound sources exceed levels that are likely to entail signi?cant impact on marine animals (Com. Dec. 2010/477/EU). Commission Decision (EU) 2017/848 detailes further criteria elements for the 11 qualitative descriptors and speci?es methodological standards for the scale of the assessment, 2 C. Juretzek et al.