In Croatia the many ferry routes are operated by 12 different companies, and not only Jadrolinija as many websites mistakenly imply, so if you want to check all ferry connection here is the place to do so
For ferries in Croatia the following applies.
It is not possible to book and reserve ticket on local lines
It Is possible to book ticket for International ferry lines to and from Italy
In main season, most ferry ports are packed with cars, so be sure to arrive in due time!
The main ferries ports, is Dubrovnik, Split, Zadar and Rijeka
From Dubrovnik there is (among others) ferry or catamaran connection to, Bari Italy, Mljet, Korcula, Hvar, Split, Rijeka
From Split there is (among others) ferry or catamaran connection to, Ancona Italy, Vis, Hvar, Brac, Korcula, Dubrovnik, Solta, Drvenik
From Zadar there is (among others) ferry or catamaran connection to, Ancona Italy, Pasman, Ugljan, Pula, Dugi Otok
From Rijeke there is only a few ferry connections, e.g to Island Rab.