Biyun Cave

　　Biyun Cave is located south of the ancient city of Pan County and is a natural karst cave, recognized as a member cave by the International Union of Speleology. The cave stretches 6.5 kilometers in length and is formed where three streams converge, hence it is also known as the "Water Cave." Biyun Cave features three interconnected passages: one leads into an underground passage, another allows light to filter through from a sky window, and the third serves as a ventilation outlet for water. The Ming Dynasty's "Tongyi Zhi" (Unified Gazetteer) referred to it as

　　"the foremost wonder of Pu'an Prefecture." The cave scenery is divided into the Water Cave and the Dry Cave. The Water Cave has both an entrance and an exit, which are over 10 kilometers apart, with an underground stream running through and exiting via the Wind Cave into the Nanbanqiao River. Entering from the inlet to Lvyintang covers about 1.5 kilometers, with widths ranging from 20 to 50 meters and heights from 30 to 150 meters. It features the “Four Wonders of the Cave” recorded by Xu Xiake: the “Hanging Dragon’s Backbone,” the “Eighteen Dragon Fields,” the “Snake Shedding Its Skin,” and the “Lion in a Crouching Position.” A local tradition of “playing at the Water Cave” is observed on the 23rd day of the first lunar month.