Солтүстік Мұздық Океанның Лаптев теңізі

Marginal sea in the Arctic Ocean north of Siberia between the Kara Sea and the East Siberian Sea

The Laptev Sea (; ) is a marginal sea of the Arctic Ocean. It is located between the northern coast of Siberia, the Taimyr Peninsula, Severnaya Zemlya and the New Siberian Islands. Its northern boundary passes from the Arctic Cape to a point with co ordinates of 79°N and 139°E, and ends at the Anisiy Cape. The Kara Sea lies to the west, the East Siberian Sea to the east. The sea is named after the Russian explorers Dmitry Laptev and Khariton Laptev; formerly, it had been known under various names, the last being Nordenskiöld Sea (мо́ре Норденшёльда), after explorer Adolf Erik Nordenskiöld. The sea has a severe climate with temperatures below 0 °C (32 °F) over more than nine months per year, low water salinity, scarcity of flora, fauna and human population, and low depths (mostly less than 50 meters). It is frozen most of the time, though generally clear in August and September. The sea shores were inhabited for thousands of years by indigenous tribes of Yukaghirs and then Evens and Evenks, which were engaged in fishing, hunting and reindeer husbandry. They were then settled by Yakuts and later by Russians. Russian explorations of the area started in the 17th century. They came from the south via several large rivers which empty into the sea, such as the prominent Lena River, the Khatanga, the Anabar, the Olenyok, the Omoloy and the Yana. The sea contains several dozen islands, many of which contain well preserved mammoth remains.

The Lena River, with its large delta, is the biggest river flowing into the Laptev Sea, and is the second largest river in the Russian Arctic after Yenisei. Other important rivers include the Khatanga, the Anabar, the Olenyok or Olenek, the Omoloy and the Yana. The sea shores are winding and form gulfs and bays of various sizes. The coastal landscape is also diverse, with small mountains near the sea in places. In the northern part, the sea bottom sharply drops to the ocean floor with the depth of the order of (22% of the sea area). There it is covered with silt, which is mixed with ice in the shallow areas.

The climate of the Laptev Sea is Arctic continental and, owing to the remoteness from both the Atlantic and Pacific oceans, is one of the most severe among the Arctic seas. Polar night and midnight sun last about three months per year on the south and five months on the north. Air temperatures stay below 0 °С 11 months a year on the north and nine months on the south. The average temperature in January (coldest month) varies across the sea between and and the minimum is In July, the temperature rises to 0 °С (maximum 4 °С) in the north and to 5 °С (maximum 10 °С) in the south, however, it may reach 22–24 °С on the coast in August. The maximum of was recorded in Tiksi. Usually, ice formation starts in September on the north and October on the south, though it has progressively begun later because of human driven climate change. In 2020 Siberia experienced record breaking heat and formation did not begin until late October, marking the latest start ever recorded. The ice formation results in a large continuous sheet of ice, with the thickness up to in the south eastern part of the sea as well as near the coast. Those tribes were engaged in fishing, hunting and reindeer husbandry, as reindeer sleds were essential for transportation and hunting. They were joined and absorbed by Evens and Evenks around the 2nd century and later, between 9th and 15th centuries, by much more numerous Yakuts. All those tribes moved north from the Baikal Lake area avoiding confrontations with Mongols. Whereas they all practiced shamanism, they spoke different languages. Russians started exploring the Laptev Sea coast and the nearby islands some time in the 17th century, going through the rivers emptying into the sea. Many early explorations were likely unreported, as indicated by graves found on some of the islands by their official discoverers. In 1629, Siberian Cossacks went through the Lena River and reached its delta. They left a note that the river flows into a sea. In 1633, another group reached the delta of Olenyok. By 1712, Yakov Permyakov and Merkury Vagin explored the eastern part of the Laptev Sea and discovered Bolshoy Lyakhovsky Island. However, they were killed on the way back from their expedition by mutineering team members. In 1770, the merchant Ivan Lyakhov revisited the islands and then asked the government for permission to commercially develop their ivory resources. Catherine II granted permission and named the islands after Lyakhov. While exploring the area in the 1770s, Lyakhov described several other islands, including Kotelny, which he named so after a large kettle (котёл – kotel) left there by previous visitors. He also established first permanent settlements on those islands. In 1735, Russian explorer of Siberia Vasili Pronchishchev sailed from Yakutsk down the Lena River on his sloop Yakutsk. He explored the eastern coast of the Lena delta, and stopped to winter at the mouth of the Olenyok River. Unfortunately many members of his crew fell ill and died, mainly from scurvy. Despite these difficulties, in 1736, he reached the eastern shore of the Taymyr Peninsula and went north surveying its coastline. Pronchishchev and his wife succumbed to scurvy and died on the way back. Maria Pronchishcheva Bay in the Laptev Sea is named after the wife of Pronchishchev. During the 1739–1742 Great Northern Expedition, Russian Arctic explorer and Vice Admiral Dmitry Laptev described the sea coastline from the mouth of the Lena River, along the Buor Khaya and Yana gulfs, to the strait that bears his name, Dmitry Laptev Strait. As part of the same expedition, Dmitry's cousin Khariton Laptev's led a party that surveyed the coast of the Taimyr Peninsula starting from the mouth of the Khatanga River. Detailed mapping of the coast of the Laptev Sea and New Siberian Islands was performed by Pyotr Anjou, who in 1821–1823 traveled some over the region on sledges and small boats, searching for the Sannikov Land and demonstrating that large scale coastal observations can be performed without ships. Anzhu Islands (the northern part of New Siberian Islands) were named after him. In 1875, Adolf Erik Nordenskiöld was the first to travel across the whole sea on a steamship Vega. Toll noted sizable and economically significant accumulations of perfectly preserved fossil ivory in recent beaches, drainage areas, river terraces and river beds within the New Siberian Islands. The later scientific studies demonstrated that the ivory accumulated over a period of some 200,000 years.

The name of the Laptev Sea changed several times. It was apparently known as the Tartar Sea (Татарское мо́ре) in the 16th century, the Lena Sea (Ленское мо́ре) in the 17th century, the Siberian Sea (Сибирское мо́ре) in the 18th century and the Icy Sea (Ледовитое мо́ре) in the 19th century. It acquired the name Nordenskjold Sea (мо́ре Норденшельда) in 1893. On 27 June 1935, the sea finally received its current name after the cousins Dmitry Laptev and Khariton Laptev who first mapped its shores in 1735–1740.

Both flora and fauna are scarce owing to the harsh climate. Vegetation of the sea is mostly represented by diatoms, with more than 100 species. In comparison, the number of green algae, blue green algae and flagellate species is about 10 each. The phytoplankton is characteristic of brackish waters Rare vascular plants include species of Cerastium and Saxifraga. Non vascular plants include the moss genera Detrichum, Dicranum, Pogonatum, Sanionia, Bryum, Orthothecium and Tortura, as well as the lichen genera Cetraria, Thamnolia, Cornicularia, Lecidea, Ochrolechia and Parmelia. Permanent mammal species include ringed seal (Phoca hispida), bearded seal (Erignathus barbatus), harp seal (Pagophilus groenlandicus), walrus (Odobenus rosmarus), collared lemming (Dicrostonyx torquatus), Arctic fox (Alopex lagopus), reindeer (Rangifer tarandus) wolf (Canis lupus), ermine (Mustela erminea), Arctic hare (Lepus timidus) and polar bear (Ursus maritimus), whereas beluga whales (Delphinapterus leucas) visit the region seasonally. The walrus of the Laptev Sea is sometimes distinguished as a separate subspecies Odobenus rosmarus laptevi, though this attribution is questioned. There are several dozens species of birds. Some belong to permanent (tundra) species, such as snow bunting (Plectrophenax nivalis), purple sandpiper (Calidris maritima), snowy owl (Bubo scandiacus) and brent goose and other make large colonies on the islands and sea shores. The latter include little auk (Alle alle), black legged kittiwake (Rissa tridactyla), black guillemot (Cepphus grylle), ivory gull (Pagophila eburnea), uria, charadriiformes and glaucous gull (Larus hyperboreus). Among other bird species are skua, sterna, northern fulmar, (Fulmarus glacialis), ivory gull (Pagophila eburnea), glaucous gull (Larus hyperboreus), Ross's gull (Rhodostethia rosea), long tailed duck (Clangula hyemalis), eider, loon and willow grouse (Lagopus lagopus). There are 39 fish species, mostly typical of braskish environment;

The coast of the sea is shared by the Sakha Republic (Anabarsky, Bulunsky District and Ust Yansky districts) on the east and Krasnoyarsk Krai (Taymyrsky Dolgano Nenetsky District) of Russia on the west. The coastal settlements are few and small, with the typical population of a few hundred or less. The only exception is Tiksi (population 5,873), which is the administrative center of the Bulunsky District.

Fishery and hunting have relatively small volume and are mostly concentrated in the river deltas. Despite freezing, navigation is a major human activity on the Laptev Sea with the major port in Tiksi. During Soviet times, the Laptev Sea coastal areas experienced a limited boom owing to the first icebreaker convoys plying the Northern Sea Route and the creation of the Chief Directorate of the Northern Sea Route. The route was difficult even for icebreakers – so Lenin (pictured) and her convoy of five ships were trapped in ice in the Laptev Sea around September 1937. They spent an enforced winter there and were rescued by another icebreaker Krasin in August 1938. The major transported goods were timber, fur and construction materials. After the break up of the Soviet Union commercial navigation in the Siberian Arctic went into decline in the 1990s. More or less regular shipping is to be found only from Murmansk to Dudinka in the west and between Vladivostok and Pevek in the east. Ports between Dudinka and Pevek see next to no shipping at all. Logashkino was abandoned in 1998 and is now a ghost town.

In the 1930, deposits of coal, oil and salt were discovered around the Nordvik Bay. In order to explore them in the extreme Arctic conditions, a Gulag penal labor camp was established in Nordvik. Drilling revealed only small, shallow oil pockets in connection with salt structures with little commercial significance. However the salt was extracted on a large scale by means of forced laborers in a penal colony. From the 1930s onwards Nordvik became an important source of salt supply for the northern fisheries. Although the original prospects for oil at Nordvik did not materialize, experience was gained in the exploration for hydrocarbons within the continuous permafrost zones. This experience proved invaluable in the later exploration and exploitation of the massive oil and gas fields of Western Siberia. The penal colony was closed and its traces erased in the mid 1940s right before Americans arrived in Nordvik as allies of the Soviet Union. In the Anabar District of Sakha, in the village of Mayat there is one of the northernmost diamond mines. There are also tin and gold mines in the Ust Yansky District.

The meteorological station of Tiksi has been renovated in 2006 (for example, it has internet connection and security cameras with a wireless interface) and has become part of the Atmospheric Observatory program of the US National Oceanic and Atmospheric Administration agency. The program aims at long term, systematic and thorough measurements of clouds, radiation, aerosols, surface energy fluxes and chemistry in the Arctic. It is based on four Arctic stations at one of the world's northernmost settlements, namely Eureka and Alert in Canada (in particular, Alert is the northernmost permanently inhabited place on Earth, only from the North Pole), Tiksi in Russia, and Utqiagvik in Alaska.

The water pollution is relatively low and mostly originates from the numerous plants and mines standing on the Lena, Yana and Anabar rivers. Their waste is contaminated with phenols (0.002–0.007 mg/L), copper (0.001–0.012 mg/L) and zinc (0.01–0.03 mg/L) and is continuously washed down the rivers into the sea. Another regular polluter is the coastal Urban type settlement of Tiksi. Occasional petrol spills occurred due to navigation and petrol mining. Another major contaminant is associated with floating and sunken wood in the sea, due to decades of rafting activities. As a result, the phenol concentration in the Laptev Sea is the highest over the Arctic waters.