Habitat modelling limitations – Puck Bay, Baltic Sea – a case study**This study represents a contribution to the project ‘Advanced Modelling Tool for Scenarios of the Baltic Sea Ecosystem to Support Decision Making (ECOSUPPORT)’, which has received funding from the EC’s Seventh Framework Programme (FP/2007–2013, Grant 217246) in conjunction with BONUS, the joint Baltic Sea research and development programme, supported by the Polish Ministry of Science and Higher Education (Grant 06/BONUS/2009). It also contributes to the Habitat Mapping project (‘Ecosystem approach to marine spatial planning – Polish Marine Areas and the Natura 2000 network’, PL 0078), supported by a grant from Iceland, Liechtenstein and Norway through the EEA Financial Mechanism.