Ram Setu: ISRO Generates A Detailed Map Of Shallow Undersea India-Sri Lanka Land Bridge

The religious and cultural significance of Ram Setu is huge in Hinduism. The structure of limestone shoals is approximately 30 km long and is geologically believed to be a former land connection between India and Sri Lanka. This setu or bridge stretches between Rameshwaram Island, off the Southeastern Coast of Tamil Nadu in India to Mannar Island, off the northwestern coast of Sri Lanka.

The records of Rameshwaram temple suggest that the bridge was above sea level until 1480 and was destroyed during a cyclone. Geological evidence suggests that the currently submerged ridge once connected India and Sri Lanka. Even 9th-century Persian navigators described this as a bridge over the sea connecting India and Sri Lanka.

‘First ever study’ providing intricate details of the submerged Ram Setu
While the bridge is visible from the aerial photographs and satellite-based observations have revealed the undersea structure, those were largely focused on exposed parts of the bridge. However, recently, scientists with the Indian Space Research Organisation (ISRO) have generated the most detailed undersea map of the setu. The recently released detailed map confirms the submerged bridge as a continuity from Dhanushkodi in India to Talaimannar in Sri Lanka.

The mapping work was carried out with a US satellite. The satellite bounced laser beams off the sea floor. This established that 99.98 percent of Ram Setu is submerged in shallow waters.

This is the ‘first-ever’ study providing the intricate details of the submerged sections of the bridge. Giribabu Dandabathula, a scientist with ISRO’s National Remote Sensing Centre in Jodhpur, and his collaborators claimed the study to be the ‘first to provide intricate details’ and shared their findings in the journal Scientific Reports.

For the study, Dandabathula and his colleagues at the NRSA (Hyderabad), used the National Aeronautics and Space Administration’s Ice Cloud and Land Elevation (ICESat)-2. It was equipped with a laser-borne altimeter meant for exploring beneath the water.

ICESat-2 data was used by the researchers from October 2018 to October 2023 for creating a 10-metre resolution map, which was sharp enough to capture features of the entire length of the submerged bridge. As per the scientists’ analysis, near about the entire length of the ridge is about 8 metres above the sea bed. However, only 0.02 percent of the bridge’s volume is exposed and visible from the top. The rest portion is submerged in the sea.

The study also reveals that 11 narrow channels, which are only a few meters away, allow water to flow or water gets exchanged between the Gulf of Mannar (southwest) and Palk Strait (northeast). Even scientists believe that these narrow channels or the gaps along the ridge likely play a crucial role in protecting the structure from the ferocity of wave actions. As evident, the bridge remains exposed to the strong waves from both sides, the Gulf of Mannar and the Palk Strait. Moreover, the summer monsoon currents bring water from the Arabian Sea into the Bay of Bengal during the southwest monsoon. Similarly, the winter monsoon currents carry waters from the Bay of Bengal via Palk Strait and Ram Setu (Adam’s Bridge) into the Arabian Sea during the northeast monsoon.

As per the ISRO team of scientists, the narrow channel permits the exchange of water freely between Palk Strait and the Gulf of Mannar which reduces the impact of the waves on the ridge.

Colonial British attempts to rename Ram Setu to Adams Bridge
The Colonial British founded a settlement in Chennai in 1644. The colonial British and Christian Missionaries have tried to heavily influence the local culture with many distortions and created many false stories – naming Ram Setu as Adam’s Bridge is one such attempt to disconnect the native connection. Bishop Cadwell has written fake books that characterize Tamil as not originating from Sanskrit and seeks to create a North Indian – Dravidian divide. Keeping the same as Ram Setu would have hurt such narratives and the British have promoted the name Adams Bridge in official records.

Implications of contrasting agendas and opposition to Rama Setu
While devout Hindus undoubtedly believe that Rama Setu was built by the Engineer Nala under the direction of Bhagwan Rama. Few doubt the itihasas or want to validate it with modern facts. There are many limestone quarries in the surrounding districts near the Rama Setu on the Indian side. So logistically building a bridge from a nearby quarry is quite feasible. The debate surrounding ‘Ram Setu’ being naturally formed or man-made is a long-standing one. Moreover, it has been a subject of interest among historians, archaeologists, and geologists.

Many devout Hindus feel some mischief makers and those who want to knowingly or unknowingly continue colonial cultural aggression continue to refer to the Ramasetu as naturally made just to hurt their sentiments. Some more educated devout Hindus feel such proposers of naturally created Adam’s Bridge instead of man-made Rama setu are themselves victims of coloniality and have not yet shaken up their cultural slavery. Both these groups of devout Hindus feel that some or other person will come up with pseudo-scientific studies and make inferences to show Ramasetu does not exist.