Lena Delta Nature Reserve (Russian: Усть-Ленский государственный природный заповедник) is a Zapovednik (“scientific nature reserve”) located in the delta of the Lena River in Sakha Republic, in the far north of eastern Siberia, Russia. The reserve is divided into two subareas, and has a total land area of 14,330 square kilometres (5,530 sq mi), making it one of the largest protected areas in Russia. The delta itself has a size of about 30,000 square kilometres (12,000 sq mi), making it one of the largest in the world. It protects large concentrations of birds, including swans, geese and ducks, loons, shorebirds, raptors and gulls. It is also an important fish spawning site.

Lena Delta Nature Reserve
Russian: Усть-Ленский (государственный природный) заповедник
IUCN category Ia (strict nature reserve)
Reindeer herd crossing the Bolshaya Tumatskaya channel within the reserve (2014)
Location	Sakha Republic, Russia
Nearest city	Tiksi
Coordinates	73°10′52″N 125°18′57″E / 73.18111°N 125.31583°E / 73.18111; 125.31583
Area	14,330 km2 (5,530 sq mi)
Established	1985

The Lena's main outlets are the Trofimov (70%), Bykov and Olenek. Nearby is the settlement of Tiksi, the administrative center of Bulunsky District, on the Bykov channel.