Nanthi Kadal (Tamil: நந்திக்கடல் Nantikkaṭal) is a lagoon in Mullaitivu District, north-east Sri Lanka. The English translation of Nanthi Kadal is "the sea of conches".The lagoon is fed by a number of small rivers, including Per Aru.The town of Mullaitivu is located on land sandwiched between Nanthi Kadal and the Indian Ocean.