The Palk Strait is a 40-85 mi (64-137 km) wide strait that lies between India and Sri Lanka between Dhanushkodi, near Rameswaram in the state of Tamil Nadu in India, and Talaimannar in the Mannar island in Sri Lanka. It is studded at its southern end with a chain of shoal reefs that are collectively called Rama's Bridge, Adam's Bridge, or Pamban Bridge . Mannar Island (Sri Lanka) is found at its southern end. the strait receives several rivers, most notably the Vaigai .

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 Raj 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 Report commissioned by the Tamil Nadu government in 2004.

Like the English Channel, the Palk Strait has been taken up as a challenge by many long distance swimmers.

The Hindu epic Ramayana recounts how Lord Rama with the help of an army of Vanaras or monkeys built a bridge of stones across the sea to Lanka to rescue his bride Sita from the Asura king Ravana. Some Christians believe this mythical bridge to be Adam's Bridge. However, no conclusive archaeological evidence has been found to this effect.