The Coral Triangle Initiative on Coral Reefs, Fisheries and Food Security (CTI), adopted recently in response to the degradation of coastal and marine environments in the Southeast Asia-Pacific’s Coral Triangle, emphasises the need for using existing international and regional fora to promote implementation. Large-scale marine initiatives, including the CTI, very often must contend with a remarkably complex institutional system. This raises the question of whether and how such complexity can be conducive to marine resources management. To answer this question, this paper aims to better understand the governance context in which the CTI was established (i.e., map governance fragmentation/complexity), and explore how such a context may support the implementation of the CTI goals (i.e., examine normative interplay). To conduct this examination, it uses an objective method that allows users to view and explore institutional arrangements through a network approach. By documenting the system of existing institutions in the Coral Triangle, the study shows that the Coral Triangle governance system is illustrative of those of international environmental governance. It involves multiple policy domains, and features different institutional arrangements and variability in terms of geographical scope and main subject matter. Such a system is complex and fragmented, marked by jurisdiction and functional overlaps. The paper suggests interplay management, such as inter-institutional learning and enhancing institutional synergy, as a promising process to promote inter-institutional coordination.