Australia’s coastal‑to‑offshore transition zone is one of the most methodologically diverse regions in marine mapping programs. Products across this zone are generated using fundamentally different technologies, from shallow-water optical remote sensing and LiDAR bathymetry to multibeam acoustics spanning shallow to offshore environments, across multiple jurisdictions with inconsistent methodological standards. The resulting “white strip” represents not only a spatial data gap but also a data quality gap, where adjacent products of contrasting reliability are often integrated without transparent communication of uncertainty.
We present a composite quality‑ranking framework developed for Seamap Australia to enable systematic comparison of seabed habitat mapping data products across the coastal‑to‑marine continuum. The framework evaluates products across eight methodological dimensions that capture transitions between optical and acoustic data regimes, spatial resolution, validation rigour, habitat classification, and survey and output scale. Input data quality and ground‑truthing together account for 80% of the composite score, reflecting a quality‑in quality‑out philosophy.
The framework was applied to 119 mapping products with scores ranging from 0.9 to 5.0 (mean 3.2). Highest‑ranking products consistently combined multibeam bathymetry and backscatter, very high‑resolution inputs (sub 2m resolution), documented and statistically robust ground‑truthing, and advanced classification methods, while lowest‑ranking products relied on coarse or modelled data, limited validation and manual interpretation. Quality variability was greatest in the coastal transition zone, demonstrating the challenge of integrating optical and acoustic mapping regimes. We demonstrate how transparent quality ranking can support national integration, guide survey investment, and underpin seamless coastal‑to‑offshore seabed characterisation.