If you embark on just one excursion from Villasimius, make it the 15-minute drive south to Capo Carbonara, a protected marine park. The promontory dips spectacularly into the crystal-clear waters of the Med. Besides perfect conditions for divers, the area has some gorgeously secluded bays with white quartz sand, backed by cliffs cloaked in macchia and wildflowers. Walking trails teeter off in all directions.
Note that parts of the promontory are off-limits to the public due to the presence of a military weather station.