Mangrove forests protect the Western coast of Maharashtra from natural disasters striking from seaward and riverside. The quantity and quality of mangroves were influenced by the morphological and hydraulic characteristics of estuaries. The study aims to identify the Spatio-temporal changes that took place in the mangrove forest of Achara estuary in the last four decades since 1989. It also highlights the zonal horizontal distribution of mangrove land from its mouths to the head of the estuary. Most of the mangroves concentrate in the zone that comprises the area of 1-3 km from the mouth. A gain of 39.17% of the mangrove area shows the growth of mangroves in the study area during this period. NDVI value, which ranges from 0.123 to 0.560, acknowledged the dense and healthy status of mangroves in Achara estuary.