Coastal zones are considered to be one of the most fragile eco-regions due to rich socio-cultural heritage, biological diversity, living resources, and environmental contamination. In order to provide protection, proper assessment is indispensable. Remote sensing provides advantage over other surveying tools in terms of efficiency, economy and robust methodologies.This paper has multi-fold methodologies to demonstrate the importance of temporal satellite remote sensing data for detecting coastlines. Orissa-West Bengal coastline has been taken as experimental test site to assess the potential of Landsat series data for monitoring variations in the coastline, and suggest appropriate algorithm for detection, mapping and assessment of coastline. The study gives insights in detecting the variations in the coastline over three decades and note the differences obtained by various methods. The intention is to focus on the grave threat faced by the flora and fauna, particularly mangroves, in the area.