Coral reefs in India are one of the most ancient and dynamic ecosystems of India. The coral reefs not only provide a sanctuary to a myriad of marine life but also play a key role in protecting the coastline from erosion. India has about 7517 km of coastline including islands but mainland coast is 6100 km.

The Gulf of Mannar is a large shallow bay forming part of the Laccadive Sea in the Indian Ocean with an average depth of 5.8 m (19 ft). It lies between the southeastern tip of India and the west coast of Sri Lanka, in the Coromandel Coast region. The chain of low islands and reefs known as Adam’s Bridge or Rama Setu, which includes Mannar Island, separates the Gulf of Mannar from Palk Bay, which lies to the north between India and Sri Lanka. The estuaries of Thamirabarani River and Vaippar River of South India and the Malvathu Oya of Sri Lanka drain into the Gulf. The dugong is found here.