The present contribution argues for taking power in hydrodiplomacy seriously and claims that the hydrodiplomacy literature is too focused on the ‘puzzling’ of diplomacy at the expense of the ‘powering’. Legitimate rule needs a combination of hard (coercion) and soft power (consent). We posit that different styles can be distinguished in negotiation by focusing on the use of power resources. With this understanding, negotiations can be analysed with greater clarity. To transpose the ‘powering’ and ‘puzzling’ from the policy sciences to diplomacy, we will draw on the main schools of International Relations theory: Realism, Institutionalism, Constructivism, and Critical theory. Each of them brings insights relevant to different uses of power and in order to understand the negotiations in practice we need all four perspectives. We combine this approach with insights from a particular power typology, and various aspects of time, including uncertainty and path dependency. To exemplify our approach, we draw on a transboundary example involving state and non-state actors (dispute over the use of the Scheldt between The Netherlands and Belgium) and a local example of hydro-political interactions (irrigation system in Yemen). While the Scheldt case appears a good example of a move to common institution building over time, a closer look reveals the influence of “back tables”, popular movements and decision-making supported by crises, past traumas and future uncertainties, highlighting the time factor. The Yemeni case illustrates likewise that institutions and better arguments do not necessarily win out while different sources of power are mobilised. We conclude that a focus on institutions, as in the dominant literature, does not tell the whole story in hydrodiplomacy. Our approach enables us in a structured manner to identify additional insights about preferred styles of negotiation.