This is an exercise in optimizing the flow through a shrouded axial turbine to have the least resistance and to have optimal output and torque and energy. In this study, different variates of the original geometry of the current turbine designed by Hydrokinetic Energy Corp. (HEC) were evaluated for energy efficiency using Computational Fluid Dynamics (CFD). The objective was accomplished by a parametric study of the key geometric parameters for the shroud, the diffuser, and the hub.