Recharting India’s Maritime Border: Coastline Now Over 11,000 km

India’s coastline length revised

India’s coastline has undergone a significant revision and is now officially measured at 11,098.81 km. It marks an increase of 3,537.21 km, or nearly 47%, from the previous measurement of 7,561.60 km. The updated figure results from a major change in the methodology used to calculate the length of the country’s shoreline, as stated in a circular recently issued by the Ministry of Ports, Shipping, and Waterways.

The earlier figure—unchanged since the 1970s—had been in use across various government departments despite discrepancies. The reassessment was based on refined technical parameters recommended by the Coastal Protection and Development Advisory Committee (CPDAC) and approved during a high-level meeting convened at the National Security Council Secretariat (NSCS) in January 2024, with participation from all coastal states and union territories.

Unlike the earlier straight-line mapping approach based on outdated maps at scales of 1:4,500,000 or smaller, the updated coastline has been calculated using modern Electronic Navigation Charts (ENCs) prepared by the National Hydrographic Office (NHO). The revised methodology measures the High-Water Line using a 1:250,000 scale, aligned with WGS-84 datum and UTM zones, offering greater accuracy by factoring in detailed coastal geomorphology such as bays, estuaries, river mouths, backwaters, and tidal linkages to offshore islands, the circular said.

The most significant change has come from Gujarat, whose coastline nearly doubled—from 1,214 km in 1970 to 2,340.62 km—making it the state with the longest shoreline. Tamil Nadu, now measured at 1,068.69 km, has overtaken Andhra Pradesh (1,053.07 km) in terms of coastline length. States such as West Bengal (721.02 km) and Goa (193.95 km) also reported notable increases, while Puducherry’s coastline saw a contraction of 10.4%, primarily due to refined delineation of erosion-prone stretches.

A key reason for the dramatic increase is the inclusion of 1,298 offshore islands and islets (1,059 islands and 239 islets), whose coastlines were previously unaccounted for due to scale constraints and manual mapping limitations. The latest data uses high-resolution GIS tools to map even minor coastal contours, which were previously smoothed over in broader-scale maps.

The recalculation was initiated after the issue was flagged in 2019 by the BM-II Division of the Ministry of Home Affairs, following which the CPDAC endorsed the revised computation in its 16th meeting. The final Terms of Reference (ToR) for standardising maritime parameters were formulated in August 2023 by the NSCS in consultation with key agencies such as the Indian Coast Guard, Ministries of Home Affairs, Environment, Earth Sciences, Jal Shakti, External Affairs, and the Survey of India (SoI).

The revised coastline will be reviewed every 10 years using updated datasets. It is expected to aid in more accurate planning for coastal security, infrastructure development, climate change adaptation, and maritime boundary management.

Here is the updated state-wise and UT-wise breakdown of India’s coastline:

This recalibration marks a landmark shift in India’s maritime mapping and will likely have wide-ranging implications across governance, environmental policy, and national security planning. The coastline length of India will be reviewed every 10 years using updated data sets.

Team BharatShakti

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