We were staying in Italy, so we had plenty of time.
There is boat service that goes to all the five towns. You can get off and on, but this is an all day event.
Carnival Liberty New Year's Eve 2007
Liberty of the Seas 5/2008+11/2009
Allure 1/16/ 2011
Independence of the Seas 12/29/2013 Top-notch!