Answer : 4. "Lagoon"
Explanation :

Pulicat Lake, saltwater lagoon on the Coromandel Coast of Andhra Pradesh state, southern India. It extends from the extreme southeastern portion of Andhra Pradesh into the adjacent portion of Tamil Nadu state and has a length of about 30 miles (50 km) and a width of 3 to 10 miles (5 to 16 km).