The following information has been taken from WikiTravel

Because Venice is on a lagoon, the water plays a crucial role in transportation. Whichever way you arrive, the last part of your journey will be on foot from the nearest waterbus/watertaxi jetty. If you need to carry or wheel bags along the narrow streets, bear this in mind when choosing your hotel location and route to it.

By plane

Take advantage of the discount with Star Alliance airlines here.

The closest commercial airport is Marco Polo Airport (IATA: VCE), on the mainland near Mestre (technically part of the city of Venice but on the mainland and without Venice’s unique structure). There is a city bus and a shuttle bus from Marco Polo to Piazzale Roma. See the details in the “By bus” section below.

Treviso Airport (IATA: TSF) is 25km (16 mi) from Venice and is relatively small but becoming increasingly busy as the main destination for Ryanair, Wizzair, and Transavia budget flights. From Treviso Airport to Venice and Mestre,Barzi Bus Service offers a €18 (Oct 2014) round-trip ticket price to Venice. These tickets are also available on their bus.

From the airport to the city centre

The airport is connected to the railway station of Mestre, opposite the city and convenient for connections to Milan, Padova, Trieste, Verona and the rest of Italy; to the railway station of Venice (5 minutes’ walk from Piazzale Roma); and to the bus terminal of Piazzale Roma in Venice by scheduled bus services. You can take a bus, a taxi or also you can discover the unique experience of a water taxi.

Water taxi is also the most comfortable (and expensive) way to arrive directly to your hotel in Venice, to Venice Cruise Port terminal and to Lido di Venezia (a big island in front of Venice).

Water taxi departures are 10-15 minutes’ walk from the Marco Polo airport. From the arrivals hall exit, turn to your left through the airport grounds to the boat departure point. Here you will find free trolleys to carry luggage for the short trip to the water taxi departure point. There are also some companies that offer porter services and/or private minivan transfer from the airport to the water taxi departure point.

Depending on the kind of service requested (meet & greet, luggage assistance, minivan transfer or simply water taxi) the price can run from €100 to €160 (4 people with luggage) from Marco Polo Airport to Venice City Centre or to the Cruise Port Terminal. Every additional passenger costs €10-20. A maximum of 10 people can take one standard water taxi.

The price for a shared transfer will be €35 per passenger, but in this case you will have to wait for other passengers until the water taxi will be full.

When you exit the airport, the ACTV bus #5 will be on your left and the ATVO bus will be on your right; both will take you to Piazzale Roma (the only part of the city of Venice that you will be able to reach with ground transportation).

By train

Trains from the mainland run through Mestre to the Venezia Santa Lucia train station on the west side of Venice; make sure you don’t get confused with Venezia Mestre which is the last stop on the mainland. From the station district, water buses (vaporetti) or water taxis can take you to hotels or other locations on the islands, but walking is usually the best option. Direct trains to Venice are available from many international destinations, there are overnight trains from Munich, Paris and Vienna and also a weekly long-distance night train (four nights) from Moscow via Kiev,Budapest and Zagreb. One of the best ways to arrive to Venice by train is with the legendary Venice Simplon-Orient-Express. The local handling agent can do reservations and take care of all the transfers from the train when you arrive. Venice is well-connected with the domestic train network,Rome and Milano are only a few hours away. Also there are some night trains from cities in southern Italy, though since 2012 most services have been cancelled.