In Venice, public boats are called vaporetti and motoscafi and they are running constantly, after every few minutes. The most frequently used waterbus by tourists is the local one numbered No. 1 and it stops 13 times between the Piazzale Roma and the Piazza San Marco. For details on boat routes, see www.actv.it
The usual fare for a waterbus or autobus is very high €6,50 for one hour. For those who plan to travel extensively by public transportation it is advisable to get a 12- to 72-hour "tourist travel card" from ACTV, the Venice transit authority. This will save a lot of money. In addition to this a Cartavenezia card is also available for residents, students, and visitors who are planning on staying on for a while as it offers large discounts on public-transportation fares. This card is not practical for short-term visitors.
When traveling in a small boat if a ticket booth does not exist, ask the conductor for a ticket (biglietto) as soon as you board the vaporetto. Traveling without a ticket could result in a heavy fine and public embarrassment.