Acoustic waves remain the workhorse of underwater communication because they can travel much farther than EM or optical signals. Operating roughly between 2.5 kHz and 180 kHz, underwater acoustic communication (UWAC) can support long‑range links but at the cost of lower data rates, higher latency and complex channel conditions. Sound speed varies with temperature, salinity and depth, creating sound velocity profiles that bend and trap sound, while multipath reflections, Doppler effects and environmental noise further complicate reliable data transfer.

The publication discusses how these physical constraints affect coverage, reliability and environmental impact, including potential harm to marine life from intense acoustic sources. It compares acoustic, EM and optical technologies in terms of range, data rate, latency, energy consumption, cost and environmental sensitivity, and emphasises that no single technology is “best” in all situations.

For UnderSec, this clearly points towards hybrid underwater communication networks that combine the strengths of each approach—acoustic for long range, optical for high‑rate short links, EM or emerging magnetic‑induction methods for niche cases—to support monitoring, detection and control around critical underwater infrastructure.