<p>This paper addresses the problem of the trajectory tracking control of an unmanned under-actuated surface vehicles (USVs) in the presence of un-modeled dynamic, model parameter uncertainty and environmental disturbances using an fuzzy-adaptive backstepping-based dynamic sliding mode control (FABDSMC) scheme. Firstly, the kinematic and dynamic model of the unmanned USV is presented in horizontal plane. Then a sliding mode control approach is combined with backstepping technique to find out the control laws corresponding the control inputs as well as adaptive laws for estimation of uncertain terms. Subsequently in order to avoid chattering phenomena, a fuzzy controller is used to determine the switching gains in the control laws based on the defined sliding surface and its time-derivative. Finally, the effectiveness of the proposed control approach is demonstrated via simulation results.</p>