This dataset provides a curated Excel-based database of metamaterial unit cells intended to support the marine energy research community in the design and analysis of innovative marine energy systems. The database compiles geometric and mechanical information for a wide range of unit cell topologies, enabling rapid visual assessment, geometric reconstruction, and systematic classification based on functional behavior. Each entry includes a visual figure, bibliographic reference with DOI, coupling mode, nonlinear or buckling behavior classification, and both demonstrated and potential applications in the context of marine energy. The dataset also includes detailed data required to reconstruct each unit cell geometry, such as coordinate matrices (nodal coordinates and indices), connectivity matrices (element connections), and schematic skeleton diagrams with node numbering. These data formats are compatible with MATLAB and other finite element preprocessing tools. While the coordinate and connectivity data have been regenerated for consistency, they may not exactly replicate those from the original publications.