Tensions over freshwater use and management in international river basins are one of the main concerns in political relations. They may exacerbate existing tensions, increase regional instability and social unrest. Hydro-political interactions are here defined as episodes of cooperation or conflict between countries over transboundary water resources. The probability index presented in this map is based on past hydro-political issues in international river basins and a selection of biophysical and socioeconomic indicators (for the period 1997-2012). Areas are more (red) or less (blue) likely to experience transboundary water-related issues. A higher likelihood identifies areas where hydro-political interactions are more probable, due to lack of water supply and/or human pressure in a more vulnerable institutional and socioeconomic context. This data driven index can help policy makers identify areas where cooperation over water should be actively pursued to avoid possible tensions, especially under changing environmental conditions.