The Lena River in Siberia is one of the longest rivers in the world. It flows northeast and then north from its source in the Baikal Mountains south of the Central Siberian Plateau, and it empties into the Arctic Ocean via the Laptev Sea. At the mouth of the Lena River is a delta that is about 250 miles wide. The delta is frozen tundra for about 7 months of the year, but spring transforms the region into a lush wetland for the remainder of the year. Part of the area is protected as part of the Lena Delta Wildlife Reserve.