D66 is a state road in Croatia, connecting A9 motorway with D8 state road in Matulji. D66 road serves as a connection to a number of towns and resorts along the eastern coast of Istria peninsula, including Opatija, Lovran and Ičići, as well as to Brestova ferry port, from which Jadrolinija ferries fly to island of Cres (D100). The northern terminus of the road also provides a link towards Rijeka via D8 state road and to Matulji interchange on A8 motorway. The road is 90.1 km long.