Apart from pilgrims, Rameswaram is of great interest to marine biologists for; in the waters surrounding the island are beautiful coral reefs. These islands on the west of the Pamban Bridge are an ideal place to explore the sea. 20 kms away, these islands lie between the mainland and the Reefs and can be reached via Mandapam. Completely surrounded by a chain of coral reefs, the shallow waters sustain a remarkable variety of marine life - Starfish, Algae, Sea cucumbers, Crabs, Sponges and many more. There is a famous shrine of Raja Rajeswari Amman about 35 kms from Ramnathapuram built inside a palace. The Gulf of Mannar has been declared as a Bio-sphere Reserve that is being developed as an ecologically sensitive area.