A submerged section of the Great Wall of China has reappeared after 40 years underwater. The 500-year-old section in China's Hebei Province has surfaced due to increasing water drainage from the reservoir where it is situated.

Footage posted by Shanghai Daily shows the remains of the wall, which was built during the Ming Dynasty and served as a pass to the north and north-eastern frontiers.

The part of the wall, in the Kuancheng Man Autonomous County, was submerged in the 1970s when a huge reservoir was built in the region. The Panjiakou Dam is located on the Luan River and provides water to the cities of Tianjin and Tangshan. Known as the Underwater Great Wall, the site served as something of a tourist attraction, with diving and boat trips to the area.

While the section can sometimes be seen from the edge of the reservoir during droughts (when the water level drops) it is now fully visible because of an increase in agricultural and industrial activities downstream.