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 (Russian: 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.
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 and has a total concentration of about 0.2 mg/L. There are about 30 species of zooplankton with the concentration reaching 0.467 mg/L. The coastal flora mainly consists of mosses and lichens and a few flowering plants including Arctic poppy (Papaver radicatum), Saxifraga, Draba and small populations of polar (Salix polaris) and creeping (Salicaceae) willows. 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 major ones are grayling and Coregonus (whitefishes), such as muksun (Coregonus muksun), broad whitefish (Coregonus nasus) and omul (Coregonus autumnalis). Also common are sardine, Arctic cisco, Bering cisco, polar smelt, saffron cod, polar cod, flounder and Arctic char and inconnu.
In 1985, the Ust-Lena Nature Reserve was established in the delta (from Russian: устье – ust, meaning delta) of the Lena River with an area of 14,300 km2. In 1986, New Siberian Islands were included into the reserve. The reserve hosts numerous plants (402 species), fishes (32 species), birds (109 species) and mammals (33 species).