Huaga Tiankeng

　　    Huaga Tiankeng is located 10 kilometers from the steep cliffs on the northern side of the Liuche River Gorge, a tributary of the Beipan River. It is commonly known among locals as "Yangtian Mawo" or Tiankeng. This is a super-large collapsed doline with an upper opening measuring 960×520 meters and a depth of over 260 meters. The surface area of the Tiankeng’s opening reaches 354,900 square meters, making it the largest in China and among the biggest in the world. The academic term for "Tiankeng" is collapsed doline — a closed negative landform created when the roof of a massive cave collapses to the surface. A large karst cave located 100 meters south of the Tiankeng, beneath the steep cliff, serves as its drainage tunnel.