It has been described as the world's largest unbroken lowland—more than 50 percent is less than 330 feet (100 m) above sea level—and covers an area of about 2.6–2.7 million km² which is about one third of Siberia, extending from north to south for 1490 mi (2,400 km), from the Arctic Ocean to the foothills of the Altay Mountains, and from west to east for 1,180 mi (1,900 km) from the Yenisei River to the Ural Mountains.