To reverse this negative trend, it is essential to implement advanced biodiversity protection into environmental and maritime policies and practices at all governance levels: international, EU, regional, national, and local. This process of ‘biodiversity mainstreaming’ still faces certain gaps. In this blog, Päivi Haapasaari (Senior Research Scientist, Finnish Environment Agency, SYKE), Volcy Boilevin (Ph.D. candidate, Nantes Université) and Riku Varjopuro (Senior Research Scientist, Finnish Environment Agency, SYKE) explore potential reasons for these shortcomings.