This contribution points out that while the importance of hydrologic, geomorphic, ecological, temporal, and socio-cultural connectivity in the functioning of hydrosystems has been acknowledged in three dimensions (longitudinal, lateral, and vertical), vertical connectivity has often been overlooked. Drawing on a multidisciplinary literature review, the authors aim to highlight the socio-cultural connectivity of subsurface flows and aquifers as a crucial factor for socio-hydrosystem understanding and management. The piece builds on emergent literature which underscores how groundwater, shallow groundwater, and the hyporheic zone are coproduced by nature and society through time. Furthermore, the review explores how verticality has become an important heuristic dimension at the intersection of the environmental and social sciences, and there has been a particular focus on the hyporheic zone to look at how notions of interstitiality and (in)visibility can be better integrated with socio-hydrosystem science and management. Finally, the paper calls for further research to integrate the vertical dimension of hydrosystems into more comprehensive socio-hydrological frameworks, which remain, at times, empirically and theoretically weak on questions of social power, even if they do incorporate aspects of political systems. Especially as societies’ relationships to groundwater may be at the heart of climate change adaptation strategies, greater consideration of the social connectivity to subflows is a necessary direction for sustainable water resource management and scholarship.