The strait is relatively shallow. The region around Ram Setu/Adam's Bridge is typically around 1–3 metres deep, while the central part of the strait is typically around 20 metres deep, with the strait reaching a maximum depth of 35 metres.[6]
Due to lowered sea levels during the Last Glacial Period (115,000-11,700 years Before Present) where sea levels reached a maximum of 120 metres below present values, the entirety of the relatively shallow strait was exposed as dry land. Following the rise to present sea levels during the Holocene, by around 7,000 years ago, the strait became submerged.[6]
History
In 1914, there used to be regular trains from Madras/Chennai to Dhanushkodi, a ferry to Talaimannar on Mannar Island, and then a train to Colombo. In 1964, a cyclone destroyed Dhanushkodi and the railway and caused severe damage along the shores of Palk Strait and Palk Bay.[7] Dhanushkodi was not rebuilt and the railway from Talaimannar to Mahawilachchiya in Sri Lanka was given up due to the civil war (It was later completely rebuilt). At least into the 1970s there was a ferry between small piers in Rameswaram and Talaimannar, but this was discontinued.[8] Ferry service briefly resumed around 2010 but at this time there are no passenger connections across the Strait.
Proposed canal
The shallow waters and reefs of the strait make it difficult for large ships to pass through, although fishing boats and small craft carrying coastal trade have navigated the strait for centuries. Large ships must travel around Sri Lanka. Construction of a shipping canal through the strait was first proposed to the British government of India in 1860, and a number of commissions have studied the proposal up to the present day. The most recent study of the Sethusamudram Shipping Canal Project, as it is now called, was an environmental impact assessment and a technical feasibility study commissioned by the Tamil Nadu government in 2004.[9]
However, the plan encountered opposition from various religious circles. The Indian epic poemRamayana, written thousands of years ago in Sanskrit and an important Hindu text, recounts how Rama, with the help of an army of vanaras, built a bridge of stones across the sea to Lanka to rescue his wife Sita from the Asura king Ravana. The Ram Karmabhoomi movement, encouraged by a NASA satellite photograph of Rama's Setu, was formed to prevent the shipping canal from being built.[10]