For the first two decades after the Cold War, Russian naval power hardly featured in the Euro-Atlantic community's strategic thinking. This began to change in the mid-2010s, as the idea that the Russian navy poses a threat to NATO began to gain ground. That threat took shockingly real form in February 2022, when Moscow launched its invasion of Ukraine. The sea in Russian strategy is the first sustained examination of Russian maritime power in the period since the fall of the Soviet Union. It brings together leading specialists from public policy and academia to reflect on historical and contemporary aspects of Russia's naval strategy and capacities. At a time of mounting tensions, which some observers have named the 'Fourth Battle of the Atlantic', the book offers an informed and nuanced discussion, taking into account the view from Moscow and how this differs from western perspectives. It sketches a trajectory of Russia's power at sea and reflects on current capabilities and problems, as well as Moscow's strategic planning for the future.