Originally Posted by Perche

No. Alilaguna is for airport to SM and for SM to the cruise terminal. Alilaguna is the small private company that only has a couple of vaporetto routes, including the airport to San Marco (blue and red lines). ACTV is the city vaporetto that goes everywhere else, and that you will need a 3 day pass for because it will be the backbone of your transportation.

You just need an Allaguna ticket from the airport to SM and anther ticket for 3 days later fom SM to the cruise terminal. You need a 3 day ACTV pass so you can ride the ACTV vaporetti ad lib, as many times a day as you need to instead Paying 7.5 euros each time for each one of you.