In this paper we study the interaction of water waves with a surface-piercing truncated metamaterial cylinder consisting of two overlapping arrays of closely-spaced vertical thin plates. The fluid resonance promoted in the narrow vertical channels formed by the metamaterial cylinder is exploited by a novel design concept of the wave power converter by covering the surface of the cylinder with an array of small cuboid buoys which float in the gaps between the intersecting plate arrays. Each buoy is attached to its own spring and power take-off damping mechanism and the vertical displacement of individual buoys is replaced by a continuous two-dimensional function of position which follows from homogenisation of the plate/fluid structure of the cylinder. Effective medium equations and boundary conditions are derived under both full depth-dependent theory and shallow-water theory allowing semi-analytical methods to be developed to investigate the wave scattering and wave energy absorption properties of this metamaterial cylinder. Results illustrate that the internal resonance of the metamaterial cylinder can lead to significant wave power capture across a broad range of frequencies.