Yet, what Sardinia is most famous for is its stunning beaches and incredibly clear waters, that make it a paradise in the summer. Costa ReiOn the southeast of Sardinia about an hour drive from Cagliari, Costa Rei is not only one of the most incredible beaches in Sardinia, but one of the most amazing beaches in the world. How to make the most of Costa Rei: As pretty much the rest of Sardinia during summer months, Costa Rei gets crowded, especially on weekends. How to make the most of Cala Goloritze: Cala Goloritze is tiny and gets packed in the busiest summer months. As with the rest of Sardinia, Cala Domestica gets crowded during the summer months and especially during weekends.