Siberia is a vast Russian province encompassing most of Northern Asia, with terrain spanning tundra, coniferous forest and mountain ranges including the Ural, Altai and Verkhoyansk. Lake Baikal, in its south, is the worlds deepest lake, circled by a network of hiking paths called the Great Baikal Trail. The Trans-Siberian Railway passes Baikal on its route between Moscow and the Sea of Japan. Lake Baikals largest island, Olkhon, is a center of shamanism marked by Shaman Rock, an outcropping held sacred by indigenous islanders. The city of Irkutsk, the western gateway to Baikal, offers classical Russian architecture and Russian Orthodox churches. The Altai Mountains are river-rafting and mountaineering destinations with diverse wildlife and ecosystems.