Despite scathing reviews on TripAdvisor, our experience on the Catania hop-on hop-off bus was good. The driver was friendly and made sure he knew who was coming back with him at each of the stops (Aci Castello and Aci Trezza) and gave us a good pointer for lunch back in Catania. The headphones (actually earbuds) worked fine.
Round Trip: 80mins
How Often: 60mins (summer) 90mins (winter)
Starting: 9:30 (summer) 10:00 (winter)
Starts: Cathedral Square
Actually Stops: Aci Castello (after 30mins), Aci Trezza (another 10mins after that)