The Barents Sea ( BARR-ənts, also US: BAR-ənts; Norwegian: Barentshavet, Urban East Norwegian: [ˈbɑ̀ːrn̩tsˌhɑːvə]; Russian: Баренцево море, romanized: Barentsevo More) is a marginal sea of the Arctic Ocean, located off the northern coasts of Norway and Russia and divided between Norwegian and Russian territorial waters. It was known among Russians in the Middle Ages as the Murman Sea ("Norse Sea"); the current name of the sea is after the historical Dutch navigator Willem Barentsz.

The Barents Sea is a rather shallow shelf sea, with an average depth of 230 metres (750 ft), and it is an important site for both fishing and hydrocarbon exploration. It is bordered by the Kola Peninsula to the south, the shelf edge towards the Norwegian Sea to the west, and the archipelagos of Svalbard to the northwest, Franz Josef Land to the northeast and Novaya Zemlya to the east. The islands of Novaya Zemlya, an extension of the northern end of the Ural Mountains, separate the Barents Sea from the Kara Sea.

Although part of the Arctic Ocean, the Barents Sea has been characterised as "turning into the Atlantic" or in process of being "Atlantified" because of its status as "the Arctic warming hot spot." Hydrologic changes due to global warming have led to a reduction in sea ice and in stratification of the water column, which could produce major changes in weather in Eurasia. One prediction is that as the Barents Sea's permanent ice-free area grows additional evaporation will increase winter snowfalls in much of continental Europe.