The hydrogen-based energy storage and conversion system for underwater applications aims to address energy challenges in deep-sea exploration and other submerged environments. It integrates hydrogen fuel cells, which offer high energy efficiency and environmental sustaiNobility, with underwater vehicles or equipment. This system allows for extended missions by storing energy efficiently and providing reliable power without the need for constant recharging. Hydrogen’s potential as a clean energy source makes it ideal for minimizing environmental impact, especially in sensitive aquatic ecosystems. The development of this system incorporates advanced hydrogen production, storage techniques, and fuel cell technologies tailored for underwater conditions, promising significant advances in marine technology and energy solutions.