Kopački Rit, about 10 km northeast of Osijek, is one of the largest wetlands in Europe — a vast floodplain where the Drava meets the Danube, covering about 230 square kilometres of flooded forest, reedbeds, and open water. The wildlife is extraordinary: white-tailed eagles are common, black storks breed here, and during migration the reedbeds fill with waterfowl in numbers that make serious birdwatchers audibly excited.
The park is accessible by car or bicycle from Osijek (the bike path runs along the dyke). Boat trips depart from Kopačevo village and give the best access to the flooded forest interior. The visitor centre has information on current wildlife and guided tours. The best times for birdwatching are spring migration (April–May) and the autumn flood season. The park is jointly administered by Croatia and Serbia (the Danube forms the border); there is no road crossing here, only the ferry at Batina upstream.