It’s a scenic 40-minute hike from Cala Fuili, or a speedy boat ride from Cala Gonone, to this enchanting grotto. It was the last island refuge of the rare monk seal (‘bue marino’ or ‘sea ox’ as it was known by local fishers). The watery gallery is impressive, with shimmering light playing on the strange shapes and Neolithic petroglyphs within the cave. Guided visits take place up to seven times a day. In peak season you may need to book.