You can take the ATVO Express bus or a taxi from the airport to Piazzale Roma. This is the end of the line for land vehicles. From here it’s by foot to by boat. From Piazzale Roma, you can take the Vaporetto, Line 1, and get off at the second stop, Riva de Biasio. If you are traveling lightly you can try to walk, but we aware that there will be bridges to cross and it is very easy to get lost in Venice.
There is also a water service that leaves directly from the airport called Alilaguna. You would take the Orange Line and get off at the San Stae stop. To get to the dock at Marco Polo is about a 10 to 12-minute walk.
A private water taxi is also an option but be aware that this is the most expensive option by far. But, because their boats are smaller than the public transportation boats they can navigate the smaller canals and get you closer to your hotel.