The coastline of Tamil Nadu is located on the southeast coast of Indian Peninsula, and forms a part of Coromandel Coast of Bay of Bengal and Indian Ocean. It is long and is the second-longest coastline in the country after Gujarat. Chennai, the capital of the state and an important commercial and industrial center in the country is located in the northern part of the coast with Kanniyakumari, forming the southern tip where Indian Ocean, Bay of Bengal and Arabian Sea meet. It also shares maritime border with Sri Lanka across the Palk strait in Gulf of Mannar. The coastal corridor consists of 13 districts with 15 major ports and harbors, sandy beaches, lakes and river estuaries. Tamil Nadu is the only state in India with territory on the both the eastern and western coastlines.
Tamil Nadu has major seaports at Chennai, Ennore, Tuticorin and Nagapattinam. There are 11 other minor ports. Chennai Port is an artificial harbor and is India's second busiest container hub. Because of its shallow waters, Sethusamudramthe sea separating Sri Lanka from Indiapresents a hindrance to navigation through the Palk Strait. Though trade across the India-Sri Lanka divide has been active since at least the first millennium BCE, it has been limited to small boats and dinghies. Larger oceangoing vessels coming from the West have had to navigate around Sri Lanka to reach India' eastern coast. The Sethusamudram Shipping Canal Project is a proposed project to create a shipping route in the shallow straits between India and Sri Lanka which would provide a continuously navigable sea route around the Indian Peninsula.
Fishing and aquaculture
The state has a fishermen population of 1.05 million and the coast consists of 3 major fishing harbors, 3 medium fishing harbors and 363 fish landing centers. The marine fishing output from the state contributes to 10-12 % of the total marine fish production in India and is estimated at 0.72 million tonnes. Aquaculture include shrimp, sea weed, mussel, clam and oyster farming. There have been several alleged incidents of Sri Lankan Navy personnel firing on Indian fishermen fishing in the Palk Strait, where India and Sri Lanka are only separated by 12 nautical miles. Indian Government protests periodically against Sri Lankan navy for its alleged involvement in attacks on Indian fishermen. The incidents continue to happen and over 530 fishermen have been killed in the last 30 years.
Weather patterns
The Bay of Bengal is responsible for the formation of some of the strongest and deadliest tropical cyclones in the world. The basin is mostly affected by tropical cyclones. According to official estimates, more than 10,000 people were killed and hundreds of thousands made homeless when a tsunami triggered by the 2004 Indian Ocean earthquake near the Indonesian island of Sumatra struck the southern coast of Tamil Nadu on 26 December 2004. The earthquake registered 9.1–9.3 Mw, and was the largest in five decades.
Beaches
There are numerous beaches along the coast. Marina Beach in Chennai covering a distance of, is the longest natural urban beach in the country and the world's second longest.