Subsea Internet of Things (SIoT): Emerging Technologies for Marine Environmental Monitoring and Offshore Infrastructure Safety — A Critical Review

Abstract

The Subsea Internet of Things (SIoT)—often framed within the broader Internet of Underwater Things (IoUT)—is moving from pilot trials to targeted deployments for ecological sensing, offshore asset integrity, and safety-critical operations. This review critically examines enabling communications (acoustic, optical, radio frequency, and magnetic induction), networking and MAC design, localization, energy autonomy, embedded intelligence at the edge, security, and standardization. We evaluate trade-offs that shape real systems and highlight gaps that still impede reliability at scale: brittle channels, fragmented standards, fragile energy budgets, and limited cross-vendor interoperability. We argue that multi-modal links, adaptive stacks co-designed with environment-aware models, and pragmatic standards (e.g., JANUS-family profiles) are near-term levers for progress, while longer-term success hinges on trustworthy autonomy, explainable anomaly detection, and lifecycle sustainability of subsea devices.

KEYWORDS: Subsea Internet of Things, Internet of Underwater Things, underwater acoustic communication, underwater optical wireless, magnetic induction, marine monitoring, offshore safety, energy harvesting, underwater localization, JANUS.