Croatia's Catholic heritage can be seen in its celebration of Christmas, which falls on December 25 in Croatia. If you're in Croatia's capital city, do pay a visit to the Zagreb Christmas market, which appears, along with festive decorations, on the main square.
Croatia's rivers belong to the Adriatic and the Black Sea basin. The rivers in the interior are large and calmer (Sava, Drava, Danube).
Easter is celebrated with fervor in Catholic Croatia especially in Dalmatia. In some ways it is considered more religious and more serious than Christmas.