h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Flowing northwards out of Siberia's Lake Baikal is The Angara River, the only river to flow out from the world's deepest freshwater lake.

Legend has it that the 336 rivers that flow into Lake Baikal are the sons of Old Man Baikal. But Angara, his headstong and only daughter, had fallen in love with Yenisei (Russia's longest river), instead of the more trivial Irkut who he preferred for her suitor. As she fled towards her lover to the north, he threw after her a large boulder - Shaman Rock can still be seen partway between Listvyanka and Port Baikal, where the Angara leaves the lake.