This study is to further improve the hydrodynamic performance of tidal turbines by applying leading-edge tubercles to the blades inspired by the humpback whales. The study first focused on the design and optimisation of the leading edge tubercles for a specific tidal turbine blade section by using numerical methods to propose an "optimum" design for the blade section. This optimum design was then applied onto a representative tidal turbine blade. This representative 3D blade demonstrated significant benefits especially aft er stall. The experimental measurements were further validated and complimented by numerical simulations using commercial CFD software for the detailed flow analysis. Following that, a set of tidal turbine models with different leading - edge profiles was manufactured and series of model test campaigns were conducted in the cavitation tunnel to evaluate their efficiency, cavitation, underwater noise, and detailed flow characteristics. Based on these experimental investigations it was confirmed that the leading edge tubercles can improve: the hydrodynamic performance in the low Tip Speed Ratio (TSR) region without lowering the maximum power coefficient; constrain the cavitation development to within the troughs of the tubercles; and hence mitigating the underwater noise levels.