Sethusamudram (also Setusamudram, from Sanskrit; setu "bridge" and samudra "sea") is the sea that separates Tamil Nadu, India, from Sri Lanka. It encompasses the Gulf of Mannar, the Palk Strait, and a shoal of islands and bays that separate them called Ram Setu ("Rama Bridge", also known as Adam's Bridge). The name is derived from the episode recounted in the Hindu epic, Ramayana, in which Rama's army builds a bridge to cross over from Rameshwaram to Sri Lanka.
The sea is quite shallow, with a depth of less than 10 meters across most of its extent. Much of its seabed consists of limestone rock. It formed part of a land bridge that joined Sri Lanka to the continent of Asia during the last ice age.
Sethusamudram was the site of the proposed Sethusamudram Shipping Canal Project by the Government of India for dredging the entire straits to make it navigable by large ships and create fishing and shipping harbours in the coastal areas.
Advantages of this project derive from obtaining a navigable sea route close to the coast, reducing in travel distance between the western and eastern coasts of peninsular India by about 350 nautical miles (due to having to circle about the island of Sri Lanka). The project was expected to potentially transform Tuticorin into a nodal port. The Government of Tamil Nadu had also announced proposals to develop 13 minor ports, including Ennore, Cuddalore, Nagapattinam, Thondi, Valinokam, Kolachel, and Kanyakumari in the area. Criticisms of the proposed project point out the lack of need of a sea route between the western and eastern coasts of India in the first place, as it is much cheaper in terms of money as well as time to simply transport goods through land on the Indian peninsula. Apart from these criticisms, the project has been subject to a lot of debate as most Hindus hold the 'Ram Setu' as a sacred structure and oppose any project that will damage it.