Kara Sea

The Kara Sea is a marginal sea of the Arctic Ocean situated to the north of Siberia. It forms part of the system of Arctic marginal waters that also includes the Barents and Laptev Seas, with which it is closely connected both geographically and environmentally. The sea is notable for its severe climate, complex hydrography and extensive history of exploration. Its strategic importance has increased further due to the presence of significant petroleum and natural gas reserves beneath its seabed. Although icebound for most of the year, the Kara Sea has long been a central feature in Arctic navigation, resource development and scientific study.

Physical Geography and Extent

The Kara Sea is bounded by natural frontiers comprising straits, islands and archipelagos. To the west it is separated from the Barents Sea by the Kara Strait and the elongated landmass of Novaya Zemlya. To the east its limit is demarcated by the Severnaya Zemlya archipelago, which also marks the transition to the Laptev Sea. The northern limit is typically defined by a line extending from Cape Kohlsaat on Graham Bell Island in Franz Josef Land to Cape Molotov—also known as Arctic Cape—on Komsomolets Island.
The International Hydrographic Organization describes the boundaries of the sea through a sequence of capes and coastal segments, reflecting the complex interface between land and water in the Russian High Arctic. The southern limits are marked by the Siberian mainland, which hosts the mouths of several major rivers. Although precise dimensions vary by source, the sea is generally considered to be several hundred kilometres in both length and width, with a large surface area and a mean depth typical of a shallow Arctic shelf sea.
Despite its high latitude, most of the region remains unglaciated, with the exception of remote locations such as Ushakov Island. Many of its islands lie far from the coastline in open water, unlike other Arctic seas where islands cluster near the continental margin. These include the Arkticheskiy Institut Islands, the Izvesti Tsik Islands, the Kirov Islands, Uedineniya Island and Wiese Island. The most extensive island group, the Nordenskild Archipelago, comprises more than ninety islands arranged in several subgroups.

Hydrology and Oceanographic Characteristics

The Kara Sea is characterised by complex water circulation patterns influenced by seasonal ice cover, freshwater inflow and the interaction of Arctic and Atlantic water masses. It remains frozen for most of the year, typically from September to May. During the brief summer period, melting sea ice and dense freshwater discharge from major Siberian rivers—most notably the Ob, Yenisei, Pyasina, Pur and Taz—substantially modify its salinity and stratification.
These rivers collectively contribute an estimated volume of freshwater on the scale of over a thousand cubic kilometres per year, creating extensive brackish zones in the southern and central regions. Water entering from the Barents Sea plays an important role as well. This inflow, derived from modified Atlantic water, varies seasonally, with higher volumes entering during winter months.
Oceanographic modelling indicates that no single, stable circulation pattern persists throughout the year. Instead, currents depend heavily on meltwater distribution, prevailing winds and annual ice formation. This dynamic environment contributes to the broader climatic and meteorological systems of the Arctic basin, influencing regional weather and larger-scale atmospheric interactions.

Historical Exploration

The Kara Sea was labelled on early European maps under names such as Oceanus Scythicus and Mare Glaciale. For centuries, its thick and persistent ice rendered it largely inaccessible to explorers. In 1556 Stephen Borough attempted to reach the Ob River but was turned back by Arctic ice and fog. Later efforts by Arthur Pet and Charles Jackman in 1580 also failed, leading England to temporarily abandon attempts to uncover a navigable Northeast Passage.
During the eighteenth century, Russian exploration expanded considerably. Admiral Stepan Malygin’s voyage of 1736–1737 produced the first relatively accurate map of the Arctic coastline between the Pechora and Ob rivers. The most transformative voyage came in 1878, when Adolf Erik Nordenskild successfully navigated the sea aboard the Vega, eventually becoming the first explorer to complete the Northeast Passage. His wintering in the Chukchi Sea and his continued journey the following summer marked a turning point in Arctic maritime history, commemorated through the naming of the Nordenskild Archipelago.
The early twentieth century brought both intensive exploration and tragedy. In 1912 three Russian expeditions—those of Georgy Sedov, Georgy Brusilov and Vladimir Rusanov—were lost or severely hindered due to consolidated ice. Only two survivors from Brusilov’s expedition eventually reached land after a prolonged and arduous journey, bringing back logs and meteorological records of significant historical value.
Following the Russian Revolution, Arctic exploration and scientific work expanded rapidly. The number of polar stations multiplied, icebreakers became central to regional voyages and aerial reconnaissance was introduced. Surveys in the 1930s completed maps of the Severnaya Zemlya archipelago, while the discovery of Ushakov Island filled one of the last navigational gaps in the northern Kara Sea. During the Second World War, the region became the site of Operation Wunderland, a German naval effort that ultimately achieved limited results due to severe ice and weather.

Natural Resources and Economic Importance

Although remote and climatically harsh, the Kara Sea supports a number of small ports such as Novy Port and the settlement of Dikson. Its fisheries have economic value during the short ice-free period of the year. More significantly, the seabed forms part of the West Siberian Oil Basin, one of the world’s most productive hydrocarbon provinces.
The East-Prinovozemelsky field represents a major offshore extension of this basin. Exploration activities in the early twenty-first century revealed substantial undeveloped reserves of oil and natural gas. In 2014 international sanctions imposed on companies engaged in Arctic offshore exploration led to the suspension of foreign operations, including those involving international partners.

Environmental Concerns and Nuclear Waste

The Kara Sea has been the focus of global environmental concern due to the disposal of radioactive waste during the Soviet period. Between the mid-1960s and late 1980s, reactors from decommissioned submarines and other nuclear materials were dumped at various locations, particularly in the fjords of Novaya Zemlya and in the deep troughs of the adjacent seabed.
These deposits include multiple naval reactor units and both solid and liquid radioactive wastes. Subsequent assessments by international nuclear regulatory bodies indicate that most radioactive releases remain localised and at low levels; however, long-term environmental monitoring continues to be considered essential given the potential for ecological impacts in a region where cold temperatures slow the degradation and dispersion of contaminants.
The Kara Sea thus remains a significant location for environmental science, particularly concerning Arctic marine ecosystems, the long-term behaviour of radioactive materials and the effects of climate variability on fragile high-latitude environments.