I believe it's required that you show your passport in Croatia. Otherwise, it's up to you.
"A truly happy person is one who can enjoy the scenery on a detour."
Golden Princess 2009Carnival Conquest&
Grand Princess 2010Island Princess&
Grand Princess 2011Carnival Magic&
Carnival Dream 2012Island Princess&
Carnival Magic 2013Carnival Legend 2014&
Carnival Magic & Coral Princess 2015
Carnival Liberty 2016