The Kara Sea (Russian: Ка́рское мо́ре, Karskoye more) is a marginal sea, separated from the Barents Sea to the west by the Kara Strait and Novaya Zemlya, and from the Laptev Sea to the east by the Severnaya Zemlya archipelago. Ultimately the Kara, Barents and Laptev Seas are all extensions of the Arctic Ocean north of Siberia.

The Kara Sea's northern limit is marked geographically by a line running from Cape Kohlsaat in Graham Bell Island, Franz Josef Land, to Cape Molotov (Arctic Cape), the northernmost point of Komsomolets Island in Severnaya Zemlya.

The Kara Sea is roughly 1,450 km (900 mi) long and 970 km (600 mi) wide with an area of around 880,000 km² (339,770 sq mi) and a mean depth of 110 metres (360 ft).

Its main ports are Novy Port and Dikson and it is important as a fishing ground although the sea is ice-bound for all but two months of the year. The Kara Sea contains the East-Prinovozemelsky field (an extension of the West Siberian Oil Basin), containing significant undeveloped petroleum and natural gas. In 2014, US government sanctions resulted in Exxon having until September 26 to discontinue its operations in the Kara Sea.