Kopački rit is a floodplain area of the Danube River, situated in northeast Croatia at the confluence of the Drava and Danube rivers. It is one of the largest alluvial plains in Europe that extends to the north all the way to Szekszard in the Republic of Hungary. It ranges from the mouth of the Drava into the Danube, upstream along the both sides of the Danube. The Nature Park was established to preserve the remains of the floodplain ecosystems and it covers both the existing and parts of the former floodplains of these two big rivers. To the north and west of the present park’s boundaries lay important, but still unprotected floodplains of the Drava and Danube rivers that extend to Batina (north) and Donji Miholjac (west). The notion of Kopački rit in terms of the territory pertains to the southernmost part of the right embankment of the Danube, which is bound by the Drava (to the south), by the Danube (to the east) and by the Drava-Danube flood-dyke and Vemeljski dunavac to the west and north. It, in fact, encompasses an area of the present Special zoological reserve. The relief of the Kopački rit region is created by the river dynamics and the respective duration and height of the floods. As a river flows it creates bars and islands (called ada) as well as backwater channels that are in this region called “dunavac” or “stara Drava”. Floodplains are continuously shaped and influenced by the dynamics of discharge and fluctuating water levels. Floodplain waters sediment silt in one place, while in others they deepen the terrain thus giving the area its specific undulating look. In this way sloughs (i.e. depressions) and ridges (i.e. elevated terrains) arise and spread out along each other for hundreds of meters. Sloughs and ridges are long and narrow and have a specific arched appearance. The difference in height adds up to a few meters. The bottom of the Kopački Lake represents a place with the lowest height above sea level in the whole Kopački rit region – some 78 meters. Since the highest point in the Nature Park measures 86 meters above sea level, the difference is only 8 meters. Sloughs merge at the end and through a natural ditch, the so-called “fok”, enter Dunavac or Dunav. Sloughs are emptied or filled through this natural dithces. Natural dithces were frequently artificially deepened and there are also man-made channels that have taken over the function of natural ones. This particular configuration of sloughs and ridges give this region its unique look. The whole floodplain area acquires the features of a delta, and it is quite unique that the Danube, with the help of the Drava, in its middle course thus creates a so-called inner delta. A phenomenon of such format is not known among other European rivers and it makes this area globally important. If Kopački rit ever gets listed as a World heritage site it would be primarily because of this phenomenon, because many other bigger and more significant rivers in the world do not have it.