In cases where wetlands extend across national borders—such as transboundary rivers and lakes—cooperation among riparian states is indispensable for their effective management and long-term survival. This study builds upon existing research on transboundary wetlands and employs a comparative analysis of key indicators of cooperation, aligned with the recommendations of the United Nations Sustainable Development Goals (SDGs). Documentary evidence is analyzed to understand the mechanisms through which states collaborate. Accordingly, cooperation indicators—namely the existence of a shared water body, regular communication, joint management programs, and systematic exchange of data and information—are identified based on the literature on water diplomacy. These indicators are then applied to three selected wetlands: the Wadden Sea, the Okavango Delta, and Hamun. The findings reveal strong and effective cooperation in the Wadden Sea, moderate cooperation in the Okavango Delta, and minimal cooperation (virtually absent) in the Hamun wetland. The results suggest that cooperation in wetland management reaches its highest level where it has been institutionalized. Conversely, the absence of such cooperation in the Hamun wetland has accelerated the degradation and collapse of this ecosystem. This deterioration has been exacerbated by structural interventions, diversion and unsustainable withdrawals from inflows, and mismanagement on both sides, compounded by climate change and recent consecutive droughts.