Hydroinformatics emerged in 1991 when numerical modelling of water expanded its range from one that was restricted to the modelling of flows to a much wider ranging sociotechnical discipline that supports stakeholders in addressing their water-related problems. However, despite numerous advances in hydroinformatics, the current practical and research effort is still very much technocratic (or techno-centric) which in turn may restrict the potential of hydroinformatics in its scope and its reach. This Special Issue, through the compilation of thirteen papers, illustrates some of the developments and applications in the field of hydroinformatics and marks the twenty-five years of its existence. We hope that this will help to further raise the awareness of the subject and its developments and applications. In the Editorial of this Special Issue, we briefly discuss the origin of hydroinformatics and we introduce the papers that are featuring in this Special Issue. We also give a way forward for future research and application.