This paper presents a novel application of Pumped Storage Hydro (PSH) in which seawater and constructed reservoirs are used to generate renewable, gravitational potential energy. With the goal of net-zero carbon emissions by 2050, tapping hydropower as an alternative energy source is increasingly appealing to governments. The long duration storage system detailed in this paper boasts low grid reliance due to external tidal forces and solar/wind providing the necessary pumping power. Two constructed reservoirs stacked vertically differentiate this technology from traditional pumped storage hydro technologies. Penstock fed turbines generate electricity, while a pump situated at the lower reservoir increases the gravitational potential energy where it can be stored until needed. When released, the stored water creates electricity by driving a turbine, and returns to the ocean. In an open or closed loop system, the presented technology can continue creating electricity for a wide range of applications. The Long Duration Energy Storage (LDES) system presented is therefore applicable in many areas of the world and allows meaningful steps towards climate conscious energy production.