A wave follower attached to a stable boom at the research platform Meetpost Noordwijk has been deployed to conduct at sea eddy correlation measurements of stress below the level of the wave crests, well within the wave boundary layer. The instrument moves along with waves of frequencies less than 1 Hz, in a perfectly vertical fashion, with a maximum stroke of approximately 3.1 meters. Stress observations were performed using pressure anemometers, providing the vertical resolution needed for measurements at these low levels, mounted on the wave follower at some 0.5 and 1.5 m from the water surface, respectively. These measurements on the moving device were accompanied with stress measurements on the stable boom by means of a sonic anemometer. It is shown that the wave follower enables us to conduct reliable flux measurements well within the wave boundary layer, at levels as low as about 15% of the maximum wave height. Wave-coherent signals are extracted from the measurements and contributions from the wave-induced stress are compared to the turbulent stress. Further interpretation is attempted in terms of characteristics of the wave field, and in relation to surface layer similarity theory over the sea.