There is a seldom acknowledged problem of practical limitations to the principle of freedom of navigation. The United States as well as the United Kingdom, France, Japan and Turkey, to name a few, oppose excessive use of navigation freedom as defined by the United Nations Convention on the Law of the Sea (UNCLOS 1982). The author discusses divisions of seas from navigational and operational perspective (the high seas, exclusive economic zone, the case of Russian navigation in Gulf of Finland), and comments on freedom of navigation during armed conflict.