• Ocean Acoustic Tomography (OAT) has emerged as a unifying framework for reconstructing mesoscale to basin-scale ocean structure from acoustic travel times and multipath data, using vertical slices, phase information, and multi-receiver arrays to infer sound-speed and current fields [1], [13], [11], [17], [18], [6], [8].

• Matched-field processing (MFP) and modal-based parameter estimation provide a principled approach to localize sources and estimate range/depth in correlated-noise marine environments, leveraging ocean waveguide models and tomographic data [2], [18].

• Travel-time variability and bias in range-dependent/ocean channels drive methodological adjustments (e.g., phase-based travel time estimation and adiabatic range-dependence bias corrections) to improve inference of environmental fields and travel-time stability [3], [13].

• Underwater communication system design and channel characterization exploit energy-efficient coding, capacity limits, and channel models for marine environments, including bits-per-joule metrics and maritime satellite-channel models [9], [20], [5], [8].