Capo Caccia's principle crowd-puller is the Grotta di Nettuno, a haunting, underground fairyland of stalactites and stalagmites. The easiest way to get to the caves is to take the Navisarda ferry from Alghero, but for those with a head for heights, there's a vertiginous 654-step staircase, the Escala del Cabirol, that descends 110m of sheer cliff from the car park at the end of the Capo Caccia road.
Tours of the caves, which depart on the hour, last around 45 minutes and take you through narrow walkways flanked by forests of curiously shaped stalactites and stalagmites, nicknamed the organ, the church dome (or warrior’s head) and so on. At its furthest point the cave extends back for 1km, but a lot is not open to the public, including several freshwater lakes deep inside the grotto. Note that in bad weather the grotto is closed.
To get to the caves by public transport, a daily bus departs from Via Catalogna (€2, 50 minutes) in Alghero at 9.15am and returns at midday. From June to September, there are two extra runs at 3.10pm and 5.10pm, returning at 4.05pm and 6.05pm.