The issues surrounding the regimes of ice-covered areas, international straits, and passage rights of State vessels are analysed for the purpose of assessing the status of law and State practice in Russian Arctic waters. Passage through the Northern Sea Route has for decades been one of the most contentious legal issues in Soviet/Russian - U.S. relations. The jurisdictional claims of the large Arctic coastal States indicate substantial deviation from application of established law of the sea. The regimes of straits used for international navigation and passage rights of State vessels seem subordinate to the regime of ice-covered areas. The main finding is that there are certain elements of consistency in the common interpretation of existing law and the behaviour of these States. These elements seem to have put into action the process of formation of a specific customary international law, as well as implementation and interpretation of the law under the Vienna Convention on the Law of Treaties.