Palk Strait (Tamil: பாக் சலசந்தி) is a strait between the Tamil Nadu state of India and the Mannar district of the Northern Province of the island nation of Sri Lanka. It connects the Bay of Bengal in the northeast with the Palk Bay and thence with the Gulf of Mannar in the southwest. The strait is 33 to 50 miles (53 to 80 km) wide. Several rivers flow into it, including the Vaigai River of Tamil Nadu. The strait is named after Robert Palk, who was a governor of Madras Presidency (1755-1763) during the Company Raj period.

It is studded at its southern end with a chain of low islands and reef shoals that are collectively called Adam's Bridge. This chain extends between Dhanushkodi on Pamban Island (also known as Rameswaram Island) in Tamil Nadu and Mannar Island in Sri Lanka. The island of Rameswaram is linked to the Indian mainland by the Pamban Bridge.

As from 1914, there used to be regular trains from Madras/Chennai to Dhanushkodi, a ferry to Talaimannar on Mannar Island, and thence 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. Dhanushkodi was not rebuilt and the railway from Talaimannar to Mahawilachchiya in Sri Lanka was given up. There was a ferry between small piers in Rameswaram and Talaimannar, but this was discontinued till date.