Water, climate, and finance know no borders. This brings both challenges and opportunities. When it comes to freshwater, a majority of the world’s surface water flows in transboundary basins, spanning multiple federal states and countries. At the same time, most impacts from climate change are felt through the global water cycle and sub-cycles. Thus, transboundary cooperation is crucial for strengthening climate resilience. And, when done appropriately, riparian countries and river basin organizations (RBOs) can harness their unique attributes to secure adaptation financing from a range of sources.