https://en.wikipedia.org/wiki/MS_Marco_Polo MS Marco Polo is a cruise ship owned by the Global Maritime Group under charter to UK-based Cruise & Maritime Voyages, having been previously operated by Transocean ...
Most cruise ships to or from Venice dock at one of two nearby ports in the southwest corner of the historic center (between the Piazzale Roma parking garages and Tronchetto, just south-southwest of the train station).
The main port of Venice is called Stazione Marittima, and is where most Mediterranean cruises and other big ships dock.
Some smaller ships and ferries and hydrofoils to Croatia and Slovenia (and, in summer, even some larger boats when the Staz. Basilio ferry docks just to the southeast of Stazione Marittima along the Zattere.
The easiest way to figure out which one you need is, if you're just arriving in Venice, simply ask as you disembark If you're already in Venice and need to head to the port to catch a ship, make sure you ask beforehand which dock you want.
(All things being equal, your best bet is to head first to the main Stazione Marittima; you can always make your way around to the other slip if need be.) Many cruises that start or end in Venice include transportation to or from the airport.
It will inevitably cost far more than what you'd pay just doing it on your own.