This paper presents a path following control design for an autonomous surface vessel. The boat considered presents three degrees of freedom being driven by two independent propellers placed at its stern and is represented by a highly nonlinear underactuated dynamic model. The control objective is to reach and closely follow a pre-specified trajectory, operating in an environment perturbed by currents and waves. This objective is achieved through a control scheme based on the interaction of guidance laws synthesized by Lyapunov techniques and a high order sliding mode control approach based on the Super Twisting Algorithm. This methodology allows designing robust and simple controllers that avoid chattering effects on sliding surfaces, producing continuous control actions and presenting a reduced computational burden. The control performance is analyzed through representative simulations.