The problem of controlling a vessel in the presence of constant unknown disturbances requires employment of robust or adaptive control methods, like control with integral action, sliding mode control or adaptive control. All these methods have their benefits and drawbacks. In this paper we propose the use of so-called conditional integrators in the field of marine control. Conditional integrators have the robustness of integral action and sliding mode control, while avoiding their inherent drawbacks like chattering and integrator wind-up. The characteristics of conditional integrators are discussed, and their benefits are illustrated using simulations for path following and formation control in the horizontal plane.