As you soar over Xunwu County in Jiangxi Province, you'll notice how green it is, and it's all thanks to the water. Of course, water is the source of life, but how often do we think: Where does it come from?

The Pearl River is the third longest river in China, and the second largest by volume. One of its main tributaries is the Dongjiang, which supplies the industrial, domestic, and agricultural water used by 40 million people in the region. Amazingly, all the H2O in the Pearl River begins with a miniscule trickle in Xunwu, on the forested slopes of Yajibo Mountain. If you lace up your hiking boots, you can locate where it all begins.

(Aerial footage from Travelogue's Pearl River Series: Mouth to Source)