Coastline dynamics reflect the complex interrelation between the coastal processes, sea level variations, and human activities, making their long-term monitoring essential for sustainable coastal zone management. The current chapter uses the Digital Shoreline Analysis System (DSAS) through a GIS application, applying the multi-decadal satellite data to obtain the long-term shoreline modification condition over the Indian Sundarbans part along various islands. Multi-resolution satellite data have been used in this analysis to obtain the change rate using the statistical method of Linear Regression Rate (LRR), where more than two shorelines are calculated to reaching out the change rate. The present study applies the method during the 2000–2020 time period. The study highlights the long-term regression and transgression of the shoreline with a specific change rate. Long-term change of shoreline reveals the cumulative impacts of physical forces such as waves, storm surges, tides, sea level rise, and sediment transport, along with anthropogenic pressures including coastal infrastructure development and land reclamation. The results indicate a scientific basis for hazard zonation, policy-making formulation, and the possibility of adaptive mitigation strategies aimed at emphasizing coastal resilience in the context of climate change and rising sea levels.