<![CDATA[Shoreline position responds to waves, currents, tides, and sediment transport, and increasingly to human activity along the coast. Pramuka Island, the administrative centre of the Seribu Islands Regency, is often assumed to be losing land to erosion. We tested that assumption by analysing shoreline change from 2016 to 2026 along the island's four principal sides (north, east, south, and west), locating the most dynamic sector, and asking whether the observed change is natural or human-induced. Shorelines were extracted from 89 Landsat 8 OLI, Landsat 9 OLI-2, and Sentinel-2 Level-2A scenes obtained through Google Earth Engine (cloud cover below 40%) with the Modified Normalized Difference Water Index (MNDWI) and the CoastSat toolkit for multitemporal sub-pixel detection. We quantified change with the Net Shoreline Movement (NSM) and the linear regression rate (LRR), and judged significance against a detection accuracy of about 10 m. The natural coast proved to be largely stable. The north (NSM −3.3 m) and south (NSM +2.7 m) changed within measurement uncertainty, and the west accreted only slightly (NSM +16.0 m, about +1.2 m yr⁻¹). Substantial change occurred on the east side alone (NSM +106 m, about +10 m yr⁻¹), where a step-like jump in 2018–2019 coincides with the construction of coastal structures (a jetty and breakwater) and is partly an artefact of unstable detection over the reef flat rather than natural accretion. Shoreline behaviour on Pramuka Island is therefore governed by localised human intervention, not by widespread erosion. The MNDWI–CoastSat workflow is well suited to shoreline monitoring when its uncertainty is reported honestly.]]>
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