The article presents both dynamic development of the navigation regime on the river Danube as conventional international river and the regime of non-navigable use and protection of the river Danube. The analysis of navigation regime is a historical survey of various models of navigation management on the river Danube. Endeavour of small riparian states to sustain more sovereignty by navigation through their sectors is obvious as well as the efforts of large countries, including the non riparian ones to set up domination, i.e. full freedom of navigation throughout the navigable flow of the Danube. The article deals with initial bilateral conventions regulating navigation, multilateral international agreements opening the issue of impact of the European union integrations on the resolution of momentary pat position referring to the necessity to innovate the regime of navigation on the Danube. It emphasizes the importance of the Danube navigation for Croatia. The international regime of the protection and sustainable use of the river Danube, although only recently addressed, draws the attention both of the riparian states and of the European union, which based on its regulations relating to water regimes, insists on all-round protection not only of water, but also of biodiversity of the river Danube and its wider surroundings, i.e. the "catchment area" (undergroundwaters, surrounding forests, channels, wetlands). The Republic of Croatia is interested in implementing a number of general and regional (EU) international agreements and standards in a way that ensures its adequate position within the European union in future. [ABSTRACT FROM AUTHOR]