Heading west into Russia from the Chinese border, the Manchurian branch of the Trans-Siberian railway crosses the Pacific-Arctic watershed in the first night and runs along the river Hilok, of which you’ve never heard. Google Earth placemark here; rather poor photo here. (They don’t wash the windows much on the ageing N19 Vostok train. If it’s nice images you want, here’s Lake Baikal at sunset, but I’ve nothing to say about it.)
Natives of a small island, whose longest river is a mere 354 km long, become gawking rubes faced with the great rivers that drain continental masses. The 550 km Hilok runs into the Selenga, which fills Lake Baikal, which feeds the Angara, which flows into the Yenisei and the Arctic Ocean, at 5500 km from the farthest source. Amazingly, the Yenisei system was first navigated along its greatest length in 2001. And it’s only one of four Siberian rivers over 4000 km long.