Cambodia and Vietnam make up 30.6% of the total area of the Gulf of Thailand Large Marine Ecosystem (LME). Mangroves, seagrass, and coral reefs interact to create a transboundary habitat for migratory species in the area. With its potential for ecosystem services and multiple uses in the zone, transboundary governance issues need to be considered. The study aims to review current transboundary issues, existing governance indicators of engagement, integration, and completeness using a qualitative research approach for systematic review, key informant interviews, focus group discussion, and conducts risk ranking from very low, low, medium, high to very high. Based on systematic review and analysis, both countries’ coastal zones have an average level of risk ranking for transboundary coastal zone governance with medium risk (40%) for engagement for each of the agreements in place, with high risk (0.4) for integration across different arrangements, and with high risk (20%) for completeness of all formal arrangements in places. The zone was found to be at a high risk of biodiversity loss and degradation, marine pollution, ecosystem fragmentation, and climate change, as well as the absence of binding bilateral collaboration agreements, integration frameworks, the coastal habitat leads to be risky without transnational collaboration for coastal zone conservation. To distinguish the perspective of the holocoenotic environment from the sensitive administrative boundary of sovereign rights requires political will.
transboundary issues; coastal zone; governance; engagement; integration.