Before a cruise, one normally looks up the port and where exactly it's located. Easier said than done when it comes to Venice. If you want to save a buck or two, here's exact directions on how to get there from the Santa Lucia Train Station.
--As soon as you reach the front steps of the station, turn right and follow the canal.
--Go over that big ol' bridge. There are porters that will cart your luggage over if you wish. I had a husband and a freakishly strong mother to carry our bags. I got maybe halfway...probably less...before Will came back and grabbed my bag in one hand and his in the other and walked off with them.
--Once you're over the bridge, take a right. Cross over to the other side if you have an opening now, or wait until you get to the top of the hill. You should have a parking structure on your left and a low brick wall on your right.
--Follow that and loop around down to the main entrance to the ports. **You can skip this step if you like and catch the People Mover (yes, that's really the name of it) to the first stop for a euro per person**
--Keep walking until you see signs for the ships. There might be some cruise workers near the People Mover stop calling out either your ship name or cruise line name. They'll direct you or hook you up with a shuttle ride to your ship.
If you're coming straight from the airport, here's a great read for you. They give all your options.
We went the most indirect route resulting in a dead end, a few turn around moments, and an extra walk up hill for no reason. At one point we could see the port, but a fence and some sort of lot, and possibly some water was separating us from it. My mom and husband were more than happy to walk back to the People Mover or try to catch a water bus, but I was stubborn and insisted we pinch pennies for my pride's sake. The worst part? We started to walk up the correct street when we came off the bridge...but halfway up we turned around and walked another way because it didn't look right. Palms definitely met faces when we realized our mistake.