We have a 7:20 AM flight out of Venice, and are staying at a hotel near Piazza San Marco. I would like to get to the airport about 2 hours earlier. There seems to be a Alilaguna Blue line which leaves S Marco at 3:40 and arrives at the airport 4:59. Does this sound right, is this line reliable and seats always available and does that give us enough time at the airport? (I understand there is a 10 min walk to the airport)..We will have very little luggage - just a rolling carry on. Our other option seems to be a water taxi but the costs are quite high but we would be willing to go this route to make sure we don't miss our flight.