The Inertial Sea Wave Energy Converter device (ISWEC) is a Wave Energy Converter (WEC) that exploit the pitch motion of the hull, due to the presence of the waves, to produce energy. This motion combined by the rotational speed of a flywhell, due to the gyroscopic effect, induce a rotation around the power take-off’s axis (PTO’s axis), allowing in this way the production of energy. The whole device consists of an hermetically sealed hull, in which there are the flywhell and the PTO. This device is also provided by suitable mooring systems for the seabed. The advantage of this technology, is to use a device whose moving parts are not in direct contact with the marine environment, thus allowing reduced operational and maintenance costs.