17km excursion to the "Foce del Coghinas", the 3km long and 500m wide stretch of coastline, is the widest extension of dunes that exists in northern Italy. The river delta consists of small floating sand islands covered with vegetation; only directly at the sea the fresh water of the river mixes with the salt water. The Coghinas estuary invites to a birdwatching tour by boat. Here live and reproduce about 130 different genera of water birds such as herons, cormorants, mallards and gulls.
A 2-hour walk to the quiet bay of Cala Ostina is recommended.
A day trip to the small island of Asinara, formerly used as a prison island for the godfathers of the Cosa Nostra - today a national park and home to small white donkeys and used as a national park.
Bicycle tours (also with eBikes) on the island are also offered.
About 70km from Castelsardo lies the so-called little Barcelona, the "Spanish" harbour town of Alghero on the west coast of Sardinia.
The town invites you to stroll, explore and stroll.
The stalactite cave, Grotta dei Nettuno, is one of the most beautiful and largest in the entire Mediterranean.
By excursion boat from Alghero ( alternatively 656 steps), the lagoon inside can be visited (weather permitting).