Against a backdrop of increasing pressures from biodiversity loss, climate change and competing stakeholder interests, this paper examines factors influencing the implementation of marine and coastal governance approaches and their implications for achieving multifunctional marine and coastal landscapes. Based on a comparative case study of the temporally and spatially overlapping implementation of a state-driven National Park (NP) and a community-led Biosphere Reserve (BR) in the Nämdö Archipelago, Sweden, we conducted semi-structured interviews with differently positioned stakeholders to explore the dynamics shaping these initiatives. Deploying the Institutional Analysis and Development framework as an analytical framework in conjunction with a complex systems approach, the study identifies the interplay of key institutional and socio-ecological factors driving implementation processes and influencing outcomes. Results concerning the NP implementation reveal persistent disagreements between local residents and authorities, due to rigid institutional structures, limited integration of local knowledge, poor communication and competing priorities. In contrast, the BR approach is generally viewed more positively, attributed to its flexible governance and proactive integration of local socioeconomic and cultural values. This study highlights the importance of adaptive, inclusive governance that can address the trade-offs and synergies inherent in multifunctional sustainability efforts in coastal regions. By combining the stability and enforcement capabilities of the NP model with the flexibility and inclusivity of the BR approach, the paper suggests that a hybrid governance model could better balance ecological, social and economic objectives. It advocates for marine governance structures that prioritise inclusive decision-making and the integration of diverse values to better align ecological and community goals.