The territory, morphologically very varied, includes to the E, between the Drava and the Sava, the extreme edge of the Pannonian lowland (Slavonia, Podravina and Posavina). Slavonia is mainly flat, although in its western part it has a series of modest marly hills (Pozeska, Gora) which reach a maximum of 984 m (Psuni). AW of the country, the limestone reliefs of the Dinarides rise instead, with extensive karst plateaus (Gorski Kotar, Lika) engraved by deep valleys, ending overhanging the sea on the Adriatic side, where they descend with steep escarpments, while towards the interior slope more gently with a series of shelves. Along the coast almost all of Dalmatia belongs to Croatia, up to the Boka Kotorska, and Istria. The Dalmatian coast is high and rugged, with little room for coastal plains. Numerous islands face it, separated by longitudinal arms of the sea, which correspond to river valleys now invaded by marine waters. The limestone reliefs of Montenegro and the Dinaric Alps, which loom almost everywhere on the sea, both on the coast and on the islands, protect Dalmatia from the cold winds of the hinterland, but make communication with the rest of the country difficult. Even Istria has very articulated coasts due to the presence of deep submerged valleys; triangular in shape, it is divided into white Istria (northern part), yellow Istria (eastern part) and red Istria (central and western part) according to the chemical composition of the rocks (consisting mainly of limestone and sandstone) which gives a different color to the landscape. Croatia, rich in waterways, pays most of them to the Danube through the Drava and the Sava and is crossed by some rivers, more modest in size, which flow into the Adriatic (Zrmanja, Krka, Cetina, Narenta). The watershed between the Danube basin and the Adriatic basin goes from Monte Nevoso (1796 m) to the NW, crosses the karst plateaus to the W and continues towards the SE along the summit of the Dinaric Alps. Many rivers originate or reach the territory of other countries. La Culpa, which originates from a rich karst spring in the western highlands, follows the border with Slovenia for a long stretch. The Sava, which runs through central Croatia and forms the alluvial plain around Zagreb, marks the border with Bosnia for many kilometers. The Drava and the Mura, coming from Slovenia, cross Croatia and before flowing into the Danube they cross the Hungarian border. The major rivers of Istria are the Mirna (Mirna) and the Arsa, from Dalmatia the Zrmanja and the Krka: they have estuary mouths, due to the marine submersion phenomena of the recent geological past of these regions. The climate is continental in central Croatia: in winter in the internal depressions there are often temperatures of several degrees below zero, when the bora dominates the highlands. Even the climatic characteristics of Slavonia are clearly continental, while Istria is affected by a mild and maritime climate along the coast, but rather rigid inland.
According to iamhigher, the population is made up for the most part by Croats (89.6%), to a much lesser extent by Serbs (4.5%), Bosnians (0.5%), Italians (0.4%), Magyars (0.4%), Albanians (0.3%), Slovenes (0.3%) as well as other even more minority nationalities and people who have not indicated their country of origin, for a total of approx. 4%. From a demographic point of view, the overall population of Croatia, with 4,437,460 residents registered in 2001, it has shrunk compared to that recorded with the 1991 census, which counted 4,784,265 residents. This dramatic decline is due to the lowering of the birth rate not fully compensated by the lengthening of the average life span, and to the exit from the country of most of the Serbs and other national minorities after the proclamation of independence and the war of the 1990s.. The Serbs, in fact, who in 1991 formed approx. 12% of the population of Croatia and were recognized as a constituent nation of the republic, finding themselves relegated, after independence, to the rank of ethnic minority and not accepting the secession of Croatia, they in turn constituted an “independent republic” of Serbia within the Croatian territory, not recognized internationally. It, in war with Croatia, was eliminated by the Zagreb government in 1995 with a military action that caused a few thousand deaths among the Serbian population and approx. 200,000 refugees who fled the country and who subsequently no longer wanted, or were able, to return to Croatia. The positive balance between the 2001 census data and the 2003 estimates is mainly due to the returns of Croatian emigrants expatriated for work, especially in Germany and other Western European states. Croatian nationalism, Germany and Austria, which have substantial economic interests there), as well as the decision to leave the country by many residents of non-Croat nationality. The Italian community, in contrast to the other minorities, recorded growth, reaching approx. 30,000 people; its status, already agreed between the Italian and Yugoslav governments with the Treaty of Osimo in 1975, it was renegotiated in 1996 due to the disappearance of the six-republic federal Yugoslavia which had signed it at the time. The Italian minority in Croatia, residing mainly in Istria, was granted a certain degree of autonomy, including freedom of organization and use of the language. The average density presents striking differences between the urbanized and coastal areas, densely populated, and the mountainous and inland regions of Slavonia with a sparse population density. 57% (2008) of the total population is urbanized. Main cities, in addition to the capital Zagreb (785,866 residents In 2007) which is an essential hub of the country, are Rijeka (the Italian River), Zadar, Sibenik, Split and Dubrovnik (the ancient Ragusa), on the coast; Sisak, Varaždin, Osijek and Slavonski Brod in the interior. In the territory, four functional regions can be recognized, each gravitating to its own major urban center: in Slavonia the one headed by Osijek, in Croatia proper that of Zagreb, in Istria and northern Dalmatia the one with center of gravity in Rijeka, in the rest of Dalmatia the one with center of gravity in Split plus the poles of Zadar to the N and Dubrovnik to S.