The Ust-Lena State Nature Reserve was established in 1985. It is located near the Lena River estuary in Yakutia's Bulun District and covers an area of 1,433,000 hectares. The protected area also includes the New Siberian Islands, the eastern part of the Lena delta and the adjacent waters of the Laptev Sea.
The nature reserve was created with the aim of protecting and exploring the ecosystem of the delta of one of the major Siberian rivers, as well as protecting whitefish, the nesting sites of water migratory birds, Eurasia's northernmost population of black-capped marmots, and Yakutia's northernmost woodlands.
The nature reserve has a harsh Arctic sea climate. Snow covers the ground for 250-270 days of the year. During the warm season, the surface soil only thaws to depths of 10 to 120 centimetres.
One channel of the Lena River, the nature reserve's main waterway, flows through the mountainous area. However, at the mouth of the river, the main flow splits into a maze of numerous branches and transversal channels (almost all of them are navigable), forming a vast delta with plenty of shallow and deep lakes. Several islands dominate the centre of the delta. The most well-known is Stolb Island, which stands 114 metres above the water level and is worshipped by the Yakuts. A significant site in the nature reserve is Mount America-Khaya, where Arctic explorer George Washington DeLong died of starvation during an expedition to find a quick way to the North Pole. Another site of interest is ‘the Burial Site of the Buor-Khaya Mammoths' - a steep slope on the bank of the Olenyok Channel, which rises 40 metres above sea level.
It is an ice wall which melts intensively in summer. The upper part of the bank is a bone horizon which contains the remains of mostly mammoths, bison, horses, woolly rhinoceroses and other animals.
The nature reserve is home to the Khabarov and Danube research stations, which are run by the Russian Meteorological Service, the international biological station Nordenskiöld, which is the property of the Republic of Yakutia, and the research station of the Russian-German expedition Lena.
In 2000, the nature reserve was included as one of the world's unique natural sites on the UNESCO World Heritage List.