Since Russia is the largest country of all in terms of area, no wonder that it is the country that has many of the world's longest rivers flowing through its territory. The longest of those is the Yenisei-Angara-Selenga system, with a total length above 5500 kilometers, it is the longest river that drains onto the Arctic Ocean. The Selenga river has its source in Mongolia, then enters Russia south of Lake Baikal, and flows into the deepest lake on Earth as well. The Angara river drains Lake Baikal, and connects it to Yenisei River after traveling almost 1800 kilometers in Siberia.
The second longest river system is the Ob-Irtysh system. The Irtysh river originates on the Chinese-Mongolian areas of the Altai Mountains, then cuts through northeastern Kazakhstan before entering Russia, and joining the Ob river upper in the north. The Ob river empties into the Kara Sea, not far from the mouth of the Yenisei river.
The Ob-Irtysh river system
Third in the list in terms of river system length, is the Amur-Argun system. It is the longest in Russia that drains into the Pacific Ocean. The Argun rivers marks the Chinese border with Russia for almost 1000 kilometers, before joining the Shilka river, to form the Amur River, which continues on the Chinese-Russian border as well.
The fourth longest river is the Lena, which unlike the previous three, as not a river system, but a single river. Its source is only a few kilometers from Lake Baikal. Its length of 4472 km makes it the longest one of the rivers, though the first three river systems have longer added length.
To complete the top5 Russian rivers list, the Volga river comes in as fifth. It is the only on in the top five, that also touches European territory. It is also the longest river of Europe, and feeds the biggest lake on Earth, the Caspian Sea.
Other major rivers of Russia include the Vilyuy River, a tributary of the Lena river, the Kolyma river of eastern Siberia, the Ural river, which is often referred to as the border line between Asia and Europe, or the Lower Tunguska, all of which are longer than 2500 kilometers.