Recently, triboelectric nanogenerator (TENG) has been invented as a new energy technology and widely utilized in renewable and sustainable energy harvesting. Here we report a regular dodecahedron device integrated with 12 sets of multilayer wavy-structured robust triboelectric nanogenerators (WS-TENGs) for harvesting water wave energy. Each WS-TENG is composed of a wavy-structured Cu–Kapton–Cu film and two fluorinated ethylene propylene (FEP) thin films sputtered with metal electrodes as a sandwich structure. A hard ball is enclosed inside a polyhedron made by WS-TENGs as the walls; a collision of the ball with the WS-TENG in responding to the kinetic motion of water wave converts mechanical energy into electricity. A high output voltage and current of about 250 V and 150 μA, respectively, are measured by a single unit of WS-TENGs in water. Considering the units can be connected into a net structure, the average output power is expected to be 0.64 MW from 1 km2 surface area in a depth of 5 m. By the virtues of cost effective, low-carbon and environmentally friendly, the development of WS-TENGs can be a significant step towards the large-scale water wave energy harvesting and have great prospects for the blue energy.