Luan River

The Luan River (Chinese: 滦河; pinyin: Luánhé, formerly known as Lei Shui, or Ru Shui) is a river in China.

The river flows northwards from its source in the province of Hebei into the province of Inner Mongolia, and then flows southeast back into Hebei to its mouth on the Bohai Sea.

This part of the river flows near the ancient Mongol capital city of Shangdu.

Geological evidence such as the presence of suevite suggests there is an impact crater in the area.

The circular course of Luan River as it goes from Inner Mongolia back to Hebei is said to define part of the crater's outline.