The 3S River Basin is a major tributary system to the Mekong River, and is geographically defined by three major rivers: the Sekong, Sesan, and Srepok. These three rivers play a critical role in providing environmental flows and ecosystem services for both the Tonle Sap Lake in Cambodia and the Mekong Delta in Vietnam. The 3S Basin is important for the natural production of fish given high levels of connectivity and proximity to the Tonle Sap Lake in Cambodia, but further hydropower development threatens the 3S Basin’s remaining connectivity. This StoryMap explores the current status of hydropower development in the 3S Basin and identifies alternative energy development pathways which could conserve the current level of connectivity in the basin while sustainably meeting the region’s electricity needs. ArcGIS StoryMaps are web-based applications that combine narrative storytelling with integrated and interactive maps and other embedded content. StoryMaps are supported by Esri which is the global market leader for geographic information systems and a partner of the Mekong Infrastructure Tracker platform.