The growing need for sustainable and efficient power sources in underwater vehicles has led to increased exploration of alternative energy solutions. In this work, fuel cells valued for their high energy density and low environmental impact are evaluated for their potential to deliver continuous power for extended underwater missions. Additionally, two energy storage system configurations, namely batteries and supercapacitors, are analyzed based on their storage capacity and overall efficiency. To enhance energy utilization in underwater vehicles, a comparative study of various rule-based energy management strategies is carried out, incorporating experimental power consumption data and high-fidelity simulation models. This analysis aims to identify the strengths and limitations of fuel cells and storage systems in meeting the demands of underwater operations. Ultimately, the findings contribute to the ongoing development of underwater vehicle technology, with a focus on improving energy efficiency and mission endurance.