Chennai is the capital of the Indian state of Tamil Nadu. Situated on the Coromandel Coast off the Bay of Bengal, it is the biggest cultural, economic and educational centre of south India. It is the sixth most populous city and fourth-most populous urban agglomeration in India. Chennai is one of the most visited Indian cities by foreign tourists. It was ranked the 43rd most visited city in the world for the year 2015, and The Quality of Living Survey rated Chennai as the safest city in India. Chennai attracts 45 percent of health tourists visiting India, and 30 to 40 percent of domestic health tourists. As such, it is coined "India's health capital". As a growing metropolitan city in a developing country, Chennai confronts substantial pollution and other logistical and socio-economic problems.