The geological structure of the Caucasus extends to the northwest as the Crimean and Carpathian Mountains and southeastward into Central Asia as the Tian Shan and Pamirs. The Caucasus Mountains create an imposing natural barrier between Russia and its neighbors to the southwest, Georgia and Azerbaijan. Northeast Siberia and Kamchatka Northeastern Siberia, north of the Stanovoy Range, is an extremely mountainous region. The long Kamchatka Peninsula, which juts southward into the Sea of Okhotsk, includes many volcanic peaks, some of which are still active. The highest is the 4,750-meter Klyuchevskaya Sopka, the highest point in the Russian Far East. The volcanic chain continues from the southern tip of Kamchatka southward through the Kuril Islands chain and into Japan. Kamchatka also is one of Russia's two centers of seismic activity (the other is the Caucasus). In 1995, a major earthquake largely destroyed the oil-processing town of Neftegorsk. Also located in this region is the very large Beyenchime-Salaatin crater. Drainage Russia, home to over 100,000 rivers, is divided into twenty watershed districts. It has one of the world's largest surface water resources, with its lakes containing approximately one-quarter of the world's liquid fresh water. Russia is second only to Brazil by total renewable water resources. Forty of Russia's rivers longer than 1,000 kilometers are east of the Ural Mountains, including the three major rivers that drain Siberia as they flow northward to the Arctic Ocean: the Irtysh-Ob system (totaling 5,380 kilometers), the Yenisey (5,075 kilometers), and the Lena (4,294 kilometers), they are among the world's longest rivers. The basins of those river systems cover about eight million square kilometers, discharging nearly 50,000 cubic meters of water per second into the Arctic Ocean. The northward flow of these rivers means that source areas thaw before the areas downstream, creating vast swamps such as the 48,000-square-kilometer Vasyugan Swamp in the center of the West Siberian Plain. The same is true of other river systems, including the Pechora and the Northern Dvina in western Russia, and the Kolyma and the Indigirka in Siberia. Approximately 10 percent of Russian territory is classified as swampland. Russia's inland bodies of water are chiefly a legacy of extensive glaciation. Ladoga and Onega in northwestern Russia are two of the largest lakes in Europe. However, Lake Baikal is the largest and most prominent among Russia's fresh water bodies, is the world's deepest, purest, oldest and most capacious fresh water lake,