You're crossing open sea. Sardinia is 300km off the coast — no bridge, no tunnel. You fly (1 hour) or take an overnight ferry from Civitavecchia (6–10 hours). Both are excellent depending on whether you need a car.
Three airports: Cagliari (south), Olbia (northeast — Costa Smeralda), Alghero (northwest). Ryanair, Wizz, ITA, easyJet, Volotea. Fares start at €19 off-peak, July–August jump to €80–150.
Grimaldi/Tirrenia and Moby/GNV to Olbia (5.5–8h), Porto Torres (7h), Arbatax (10h). Night crossings: depart 8–10pm, arrive 6–7am. Cabin for 2: €70–120. Civitavecchia is 1h from Rome by regional train (€5).
Yes. Non-negotiable. Sardinia has no real public transport outside Cagliari. The best beaches, interior villages, archaeological sites — all require a car.
Fly if renting a car in Sardinia. Ferry if bringing your own car. In summer, book everything early.