In the North (50km from our guesthouse) there is LA PELOSA
very nice beach an water... but it is always crowded and you need to book here:
https://spiaggialapelosa.it/en/
Also to access the beach you need a mat (Ask us if you do not have it).

However you could go first to LE SALINE
and then in the evening after 6 pm to La Pelosa (you can enter for free) and then you can visit Stintino, the nearby village.

If you prefer something less touristic and nearest I suggest you MARINA DI SORSO, that is 25 km from us.
Sandy beach, 15 km long, is the longest beach in Sardinia and Italy.