There are several different ways you can get into Venice, despite the fact that it is a small island attached to the mainland by a causeway!
There are two airports that service Venice directly, Marco Polo International Airport and Treviso Airport. Marco Polo International is closest to Venice and is the busier of the two airports; Treviso is further away and is the main port of call for budget airlines like Ryanair.
Marco Polo International, situated to the north of Venice on the outskirts of the mainland town of Mestre, sees over seven million passengers annually. The airport is visited by several major airlines, including Air France, easyJet, Air One, Jet2.com, Lufthansa, bmi, British Airways and Thomsonfly. The airport has a number of car-hire companies based in the arrivals hall (Avis, Thrifty, Hertz, Budget and Europcar amongst them) and is connected to Venice by water-taxi, train and bus.
Treviso Airport, located twenty kilometres to the north of Venice, has grown dramatically in recent years. Ryanair is the main airline to use the airport facilities, though other budget airlines also fly into the airport (such as Wizz Air and SkyEurope). As with Marco Polo, Treviso offers car hire services from several major companies (Budget, Hertz, Sixt, Europcar and Avis as well as a few others) and is also connected to Venice by shuttle bus. Train services run from the town centre of Treviso to Venice.
Rome Leonardo Da Vinci Airport and Pisa Galileo Galilei Airport, though much further away than the two Venetian airports, offer a wider range of international airlines and are connected to Venice by train.
Venice does have a large train station which is located in the north-west area of the island. Venezia Santa-Lucia is linked to the mainland (and the next nearest train station, Venezia Mestre) by the car and rail causeway (Ponte della Libertà). It is possible to catch the train direct to Venice from other major cities in Italy (including Rome), as well as several cities in Europe (such as Budapest, Munich and Paris). The Santa-Lucia train station is situated at the far-west end of the Grand Canal but is nearby to a vaporetti station (water-bus) and several water taxi docks. Gondolas are also available at the steps that lead down towards the Canal.
There are several shuttle bus services that run between the two major airports nearby and the Piazzale Roma (the small car-park area of Venice that houses the bus stops and car rental offices). Scheduled services between Mestre on the mainland and Piazzale Roma are also easy to use. Tour buses and inter-city services also use Piazzale Roma.
Although the majority of Venice is pedestrianized (no vehicles on the streets), Venice does have a tarmac area (Piazzale Roma) for car parking, car rental and multiple bus stations. This means that if you decide to hire a car elsewhere in Italy or Europe, you can drop off your car at the car rental office in Venice - providing the company you hire from has an office on the island! Avis, Sixt, Hertz and National-Alamo are amongst the hire companies stationed around Piazzale Roma. If you are using your own car to get to Venice, it's advisable that you park your car on the mainland at one of the many multi-level facilities in Mestre. These car-parks are much cheaper than those at Piazzale Roma, and some offer shuttle bus transfers to Venice itself.
There are several different methods of getting to and from Venice by water-craft. Water-taxis, private boats which can be hired from several key points on the mainland and around Venice, are fast and efficient. Vaporettis, water-buses, also depart from a number of areas around the Venetian Lagoon, and are cheaper than their water-taxi cousins. Private boats can be docked around Venice, though moorings generally have to be pre-booked. Cruise ships and long-haul ferries also enter the Venetian Lagoon, docking at the Stazione Marittima.