Engineering the propagation of water waves is a crucial challenge for potential applications at oceanic scale. Despite their apparent complexity, they do not fundamentally differ from any other kind of physical wave. Similar to recent approaches in optics or acoustics, we propose to artificially manufacture materials at the sub-wavelength scale to modify the propagation characteristics at will. We demonstrate that hydroelastic waves allow for the straightforward control of the medium properties, as well as the quantitative measurement of the full wave field. We investigate propagation in hydroelastic metamaterials made from periodic arrays of tunable resonators. We fully characterize the band structures of such materials, revealing the coexistence of Bragg and hybridization bandgaps. We also introduce a theoretical approach to model this complex system and predict its band structure. These unprecedented experimental and theoretical results reveal the possibility to efficiently control water waves at the laboratory scale.