Su Portu is found in the locality of Chia, in the municipal area of Domus de Maria. Its seashore has light-coloured sand and small pebbles, and is flanked by a bluff. The tower of Chia rises on a tall promontory covered by the typical vegetation of the Mediterranean brush, at the foot of which are the ruins of the ancient Phoenician city of Bithia (8th century) and Cardolinu, an islet joined to the beach by a narrow, sandy isthmus.