Measuring sea visibility: a condition for Ocean Literacy or a sign of privilege?

IntroductionThis study reconceptualises sea visibility as a structural territorial property that conditions everyday visual exposure to the marine environment, developing and applying a comprehensive GIS-based framework to the island of Mallorca (Western Mediterranean).MethodsVisibility is analysed bidirectionally, from land to sea and from sea to land, using systematic observer grids, distance-dependent visual radii, and a dual elevation model approach comparing Digital Terrain Model (DTM) and Digital Surface Model (DSM)-based viewsheds. Distance-to-coastline weighting is applied to emphasise interactions within the coastal fringe, and cumulative visibility surfaces are aggregated to census sections to enable socioeconomic analysis.ResultsResults reveal pronounced spatial heterogeneity in structural sea visibility, strongly concentrated along the coastal fringe and shaped by the interaction of topography, coastal morphology, and surface artificialisation. The comparison between DTM- and DSM-based visibility demonstrates that buildings, infrastructure, and vegetation substantially modify potential visual relationships, with the greatest losses concentrated in densely urbanised coastal sectors. Bivariate spatial autocorrelation analysis reveals a weak but statistically significant positive association between household income and sea visual exposure at census-section level (Moran’s I = 0.106), mediated by historical settlement patterns and urban morphology rather than reflecting a simple privilege-deprivation dynamic. Extending this framework to the Blue Schools distribution, the analysis reveals that certified centres show a consistent tendency towards greater structural visual exposure at higher visibility thresholds, with the highest sea visibility values concentrated in private institutions located in socioeconomically privileged coastal areas.DiscussionThese findings suggest that sea visibility operates simultaneously as a potential enabler of Ocean Literacy and as a partially privatised territorial amenity, with implications for spatially equitable Ocean Literacy policy.