Revised Length of India’s Coastline

• Context (IE): India’s coastline was revised in 2023-24, increasing from 7,516.6 km to 11,098.81 km, marking a 47.7% increase.
• The total island count rose to 1,389, comprising 1,298 offshore and 91 inshore islands.
• The revision was led by the Survey of India (MoST) and the National Hydrographic Office (MoD) under coordination by the National Maritime Security Coordinator (MoHA).
• The coastline will now be reviewed every 10 years using advanced geospatial tools.

Reasons for the Increase in Coastline

• Higher resolution: Use of 1:250,000 scale captured finer coastal features like creeks and inlets.
• GIS-based: GIS enabled precise coastline tracing, avoiding generalised curves.
• Inclusion of islands: Previously unmapped offshore islands and coastal rocks were now included.
• High Water Line: Coastline was measured using updated tidal boundaries based on 2011 NHO data.
• Advanced tools: Drone imaging and satellite altimetry improved shoreline detection accuracy.
• Shift in method: Older straight-line mapping was replaced with detailed contour-following tracing.

Key Findings

Top Rankings

• Gujarat ranks first among states in coastline length (2,340.62 km).
• Tamil Nadu has overtaken Andhra Pradesh to become the second-longest coastal state.
• Andaman & Nicobar Islands have the longest coastline among all Indian entities (3,083.50 km).
• Lakshadweep holds the second-longest coastline among UTs (144.80 km).

Coastline Growth

• West Bengal recorded the highest percentage increase (357.6%) among all states.
• Gujarat had the largest absolute increase (+1,125.9 km) among states.
• Kerala recorded the lowest increase among states (+30.4 km or 5.3%).
• Puducherry is the only Indian entity with a contraction, showing a 4.9 km drop (–10.3%).

Islands

• Gujarat has the highest number of inshore (36) and offshore islands (108) among states.
• Andaman & Nicobar Islands have the highest offshore island count in India (836).
• Maharashtra ranks second in both offshore (105) and inshore islands (15).