Toward interoperable bathymetric data in ocean observing systems: integrating hydrographic standards and FAIR data practices

Bathymetric data are a fundamental component of ocean observing systems, supporting applications in ocean modelling, coastal hazard assessment, marine spatial planning, and navigational safety. However, these datasets remain highly fragmented due to the diversity of acquisition platforms, including hydrographic surveys, autonomous vehicles, satellite-derived bathymetry, and legacy chart products, which often differ in spatial reference systems, vertical datums, resolution scales, and metadata quality. This heterogeneity creates persistent barriers to interoperability, limiting data integration and reuse across ocean science and operational applications. This review examines best practices for improving bathymetric data interoperability within ocean observing systems by integrating hydrographic standards and FAIR (Findable, Accessible, Interoperable, Reusable) data principles. It synthesizes hydrographic measurement standards, quality assurance procedures, and spatial data processing techniques such as georeferencing, interpolation, digital bathymetric model generation, and uncertainty quantification. The review also evaluates FAIR implementation in bathymetric workflows, identifying gaps in metadata consistency, provenance tracking, and cross-platform compatibility. By linking hydrographic standards with FAIR practices, it highlights key barriers to seamless data integration, including inconsistent vertical datum usage, fragmented infrastructures, and uneven adoption of standardized protocols. Mapping the clauses of these standards onto the fifteen FAIR sub-principles shows that hydrographic standardisation already satisfies the reusability conditions demandingly, through mandatory paired depth and uncertainty encoding and quantified survey-order thresholds, while leaving findability largely unaddressed: identifiers specified by IHO S-100 are unique within an exchange set but not globally resolvable. Interoperability is met at the level of encoding but not of semantics, since the authoritative vocabulary of the domain is not published as dereferenceable identifiers. The review concludes that the binding constraint on bathymetric interoperability is not the absence of standards but the absence of machine-resolvable linkage between them, and that vertical-datum heterogeneity remains the barrier least tractable to specification alone.