Photography appreciation of London sun and moon

The longest underground river in the world, Longqiao Underground River.

An underground river is a river that we can't easily see. They flow or surge quietly underground. These rivers are mainly composed of groundwater. A large amount of surface water can also be collected into underground rivers. Rocks have been eroded and dissolved by water for many years, leading to collapse and gradually forming underground rivers.

On July 29th, 2004, the Sino-French expedition team went deep into the Longqiao underground river for the fifth time. After 12 days of hard exploration, it put pigments at the entrance of the underground river, and finally found the exit of the underground river in Banqiao by using GPS satellite locator and tracing test, thus accurately measuring the length of the underground river of 50 kilometers.

On September 25th, 2004, cave experts from China, France, Britain, Italy and the United States held an international cave seminar in London, England. The Sino-French expedition announced that the world's longest underground river was discovered at the junction of Banqiao in Enshi, Hubei Province and Xinglong Town in Chongqing, and its exit was located at Banqiao in Mufu Grand Canyon in Qingjiang River.