Ram Setu is a chain of shoals between Mannar Island of Sri Lanka and Rameswaram Island of India.
The bridge is around 50 kms long and separates the Gulf of Mannar from the Palk Strait.
Ram Setu is also called Adam's Bridge, Nala Setu and Setu Banda. You can still walk on Ram Setu for some distance where water is shallow.
The Archaeological Survey of India is doing research to determine the age and formation process of the Ram Setu.