WARNING: Travel to the border region between Croatia and Serbia to the self-proclaimed micronation of Liberland is currently extremely dangerous. Recent visitors have been given heavy fines and jail sentences. Croatian Police recently detained a member of European Parliament preventing even him from entering this area despite having a diplomatic passport.
The Kopački Rit is the biggest natural wetlands in Europe and the birdlife is spectacular. This enormous nature park, located around 15km north of Osijek where the Danube and Drava rivers flow into one another, is a great day out in the countryside - though bring some insect repellent as the mosquitos do bite!! There is no public transport to the park, so take the local bus to Bilje and its a 2-3km walk.