State Nature Reserve "Sea-Yu" is located in the Polar region of Nenets Autonomous Okrug. Creation of the reserve was November 1, 1999 according to the order of Administration of the NAO. The purpose of the reserve was not only the preservation but also a detailed study of flora and fauna Bolshezemelnoy tundra and spruce woodland relict and unique archaeological sites. The total area of ​​the reserve is 54 765 hectares, without isolation of the protected area.

One of the main attractions of the natural reserve "Sea-U" was the presence of the largest island of the relict spruce forest, located above the Arctic Circle on the territory of the tundra.

The types characterized by social and economic importance, are nesting Bean, which are characterized by an unusually high density. In addition, the Reserve carries great scientific importance as a model facility designed to monitor the condition and dynamics of forest and tundra ecosystems due to the upcoming climate change.

With regard to the historical and cultural objects, it plays an important role Habidepadara or sinful and holy forest - a forest island, which is the title of the Nenets sacred.

The most important ecosystems and landscapes are the basic values ​​of the state nature reserve "Sea-U" .  Island relic spruce is within the tundra zone and a few isolated from the dominant habitat of the Siberian spruce, formed in Subboreal period of so-called Holocene, which refers to more than 4, 5 thousand years ago .  Forest portion has character and is increasingly prevalent in the valley Sea-U .  In the direction from east to west the forest has a length of about 12 km from north to south - about 2, 5 km .  Growth of spruce trees in the area carried out by individual groups and is characterized by a greater prevalence in the warmed up on the shores of the new and the old river bed .  Existing forest island carries the exceptional interest in the issue of study and formation of the plant world, and the phenomenon of the existence of a small piece of dark coniferous taiga outside of its range . 

The natural diversity of flora and fauna of the reserve has not yet been sufficiently studied and on this point there is not enough material. Today, within the spread of complex reserve found 246 species of plants found in the sea near the island of NS.

Represented very diverse avifauna, which has about 60 species of birds. It was established that in the spruce woodland bred nest about 12 species of Siberian taiga ornithocomplexes: 1 species - Arctic, 2 species - European broad. For the territory of the complex nature reserve is characterized by high population and a wide variety of geese, swans, waders and other waterfowl, as well as the Upland Buzzard, Merlin and several predators.

In the lists of the Red Book included a large number of representatives of living on the reserve. For example, it is - 14 species of lichens, which include blackened arktotsetrariya, cladonia rough, harsh hypogymnia, hairlike brioriya, rising fistsiya and others. With regard to the vascular plants, listed in the Red Book: ortiliya blunt, two-colored sedge, rotate lomatogonium, alpine pinguicula, blackish crepis and some other species.

Under the special protection zone of the reserve "Sea-U" are: lesser white, gray ordinary shrike, golden eagle, Bewick's swan, peregrine falcon, white-tailed eagle, grouse and merlin. A total of 39 is under protection of the representatives of flora and fauna, of which 29 species are protected in the mode of state control.

The reserve "Sea-U" and strictly prohibited diversion of land and plots for construction, erection of structures and buildings, construction of roads and all types of communications, storage and application of pesticides and fertilizers, as well as mining and exploration.