Review of applications, technologies and future trends of maritime UAV systems for smart ocean operations

Maritime unmanned aerial vehicles (UAVs) are increasingly transforming ocean, coastal, port, and offshore operations through rapid sensing, intelligent communication, autonomous perception, and cooperative decision support. This trend-oriented review analyses 471 peer-reviewed journal articles published between 2020 and March 2026, supported by selected foundational pre-2020 studies, to examine the evolution, technological structure, methodological maturity, and deployment readiness of maritime UAV systems. The bibliometric analysis shows rapid publication growth, from 22 papers in 2020 to 160 in 2025, and identifies five interconnected research clusters centred on maritime communications and networking; artificial intelligence (AI)-enabled perception, surveillance, and search and rescue; navigation and cooperative operations; distributed and federated intelligence; and multi-agent autonomous systems. The literature further shows a transition from task-specific aerial monitoring toward integrated maritime cyber–physical systems combining UAVs with vessels, unmanned surface vehicles (USVs), unmanned underwater vehicles (UUVs), edge computing, next-generation communication networks, digital twins, and AI-enabled decision support. However, evidence maturity remains uneven: many AI, communication, optimisation, and cooperative-autonomy methods are still evaluated predominantly using datasets or simulation, while fewer studies provide integrated system-level evidence under representative maritime conditions. The review therefore advocates a layered validation strategy combining high-fidelity scenario-based simulation, hardware-in-the-loop testing, controlled experiments, and representative maritime trials, with traceability between simulated and observed system behaviour. Deployment readiness additionally depends on environmental robustness, interoperability, cybersecurity, energy feasibility, human oversight, maintainability, and regulatory assurance. The review therefore proposes an evidence-gated roadmap to progress maritime UAV technologies from promising algorithms and prototypes to reliable, operationally deployable smart-ocean systems.