An arrangement is provided for anti-fouling of a surface (30) of a marine structure (50) when in contact a liquid like seawater. The arrangement has floating electrodes and a power source (130) coupled to conductors in contact with the liquid, which conductors are distributed across the marine structure for providing an electrical potential across a protected area (40) of the surface. The floating electrodes (110) are arranged on the surface covering a protected area. Each floating electrode has a conductive layer being electrically isolated from the surface, and a dielectric layer (112) separating the conductive layer and the liquid. The power source is arranged to generate voltage pulses for charging and discharging the floating electrodes due to changes in the electrical potential for generating charging and discharging currents in the liquid at the dielectric layer. Effectively, such currents prevent or at least reduce biofouling.