Advanced Routing Protocols for Underwater Wireless Sensor Networks: Energy Optimization and Quality of Service Enhancement

Underwater Wireless Sensor Networks (UWSNs)represent a paradigmatic shift in marine exploration andmonitoring technologies, enabling unprecedented scientific re-search and industrial applications in aquatic environments.The unique challenges posed by underwater communication,including severely limited bandwidth, substantial propagationdelays, stringent energy constraints, and highly dynamic networktopologies, necessitate the development of sophisticated routingprotocols specifically tailored for these harsh operating condi-tions. This comprehensive survey examines the state-of-the-art inadvanced routing protocols designed for UWSNs, with particularemphasis on energy optimization strategies and Quality of Ser-vice (QoS) enhancement mechanisms. We systematically analyzecontemporary routing methodologies spanning fuzzy logic-baseddecision systems, machine learning approaches, bio-inspiredoptimization algorithms, and hybrid multi-objective techniques.Through exhaustive examination of research developments from2018 to 2025, we establish a comprehensive taxonomy of routingstrategies, evaluate critical performance metrics, and identifyfundamental design principles that govern effective underwaterrouting protocols. Our analytical findings demonstrate thathybrid approaches integrating fuzzy logic with metaheuristic op-timization algorithms consistently achieve superior performanceacross multiple dimensions, including energy efficiency improve-ments of 15-40%, packet delivery ratio enhancements of 10-25%,and significant network lifetime extensions. We provide detailedcomparative analyses through comprehensive tabular summaries,introduce novel performance benchmarking frameworks, andestablish a roadmap for future research directions in next-generation UWSN routing architectures.