Abstract: The multi-staged cowl described herein allows to increase and maximize water mass flow and pressure drop at the runner cross-section of a hydrokinetic turbine so as to maximize produced power output, while respecting dimensional constraints provided by a shallow body of water, a river for example, in which the hydrokinetic turbine can be submerged. The multi-staged cowl described herein can thus be configured so as to allow water to flow through the hydrokinetic turbine at a substantially stable water mass flow, eliminating instability, avoiding vortices, minimizing cavitation and avoiding fluid separation to negligible levels, and can include an inlet, an outlet and multiple stages which can extend between the inlet and the outlet, so that water can flow therethrough in a water flow direction.