The rivers of the province belong to the basins of the Indian Ocean and the Java Sea respectively, the water-parting being formed by the western and eastern ends respectively of the northern and southern lines of mountain peaks.
The two which drain the largest basin are the Chi Manuk and the Chi Tarum, both rising in the eastern end of the province and flowing northeast and north-west respectively to the Java Sea.
Sunda Strait is the channel separating Sumatra from Java and uniting the Indian Ocean with the Java Sea.
