Make sure you have all the needed documents with you.
The ticket alone is not enough! You must also have with you the general conditions of transport. And, in line with the Security regulations and the Circolare Serie Generale n. 106 of the Infrastructures and Transport Ministry on Safety of Navigation, all passengers, including MINORS, must arrive for boarding with a valid identity document. Otherwise, they will not be allowed on board.
Are you sailing from Italy to Corsica or vice versa? Remember that in this case you will need to show a document that allows you to leave the country.