Beautiful snorkelling with a lovely guide Andrea, very knowledgeable about the marine life in the area. The booking was slightly confusing as on their site it says "meet your guide in catania and drive along the rocky volcanic coast of Aci Castello" however we had to meet them there which did add €25 onto the trip for a taxi (no reliable buses at that time of the morning.) The fish were lovely, and Andrea was very patient with me as I'm not the most confident in the water (he gave me a life vest for peace of mind, though the wet suits are very buoyant so I probably needn't have worried.) We snorkelled straight off the marina and there was plenty to see just there, we probably spent 1.5 hours in the water though it felt like a lot less as it was so pretty. We also got 10% off on their etna trip as we did two, and that was great too :)