Nu River rises in Tibet and then flows through Yunnan Province. It is 2815 km long but of little commercial value, it passes through deep gorges and is often called China's Grand Canyon.

It is home to over 7,000 species of plants and 80 rare or endangered animals and fish. Large tracts of the Yunnanese section of the river, and it's watershed, are part of the Three Parallel Rivers of Yunnan Protected Areas, which, according to UNESCO, "may be the most biologically diverse temperate ecosystem in the world". It was designated a World Heritage Site in 2003.

The Nu people, one of the 56 ethnic groups officially recognized by China, are named after this river.