The Lena River is a major river in Siberia, Russia. It is the 11th longest river in the world and the 4th longest in Russia. It is also the second largest river in Siberia after the Yenisei River. The Lena River flows through the Sakha Republic, Irkutsk Oblast, and Krasnoyarsk Krai before emptying into the Laptev Sea. It is an important source of water for the region and is used for transportation, fishing, and hydroelectric power generation.