Grottes et karsts de Chine
Sur les traces de Xu Xiake

Xian Ren Dong

Coordinates N24.35809, E99.03793). Length:1863.70m Depth:-51.34m

The entrance of the Cave Xian Ren Dong is located at 692 m a.s.l. Fume is comes out from the entrance hole because the temperature inside is 21-22°.

It is a typical karst phenomenon, formed through the system of brittle fractures that inherited the ductile fault. The cave is formed by two major cracks with direction NE- SW and SE - NW. It is developed on 3 levels: upper, middle and lower as the first two are dry and the lower active where it flows underground river. The river is formed in the massive, and it ran out to the surface through karst spring, which is located at the foot of the massif about 40 below the cave entrance.

The cave entrance has the form of semi - ellipse with dimensions 9.20 m width and 3.43 m height. Immediately after the horizontal entrance the cave became vertical – the pit after is 9.20 m long and 3.20 m wide. The depth of the pit is 8.20 m. The cave entrance is hedged with metal bar with door which usually is locked for security reasons! The vertical part of the cave is equipped with a steep metal ladder. The following passage is steep gallery with a length of 40 meters and a slope 58 o whose width is between 8 and 9 meters. The height of the gallery is up to 16 meters. The bottom of the passage is covered with jagged gravels, in the final part with stone blocks of varying sizes. Left (in the direction of the entry) and geographical in East, there is a steep section whose final part leads to the lowest water-active level of the cave. The river passage is with total length not less than 780 m. overcoming the first (initial) part of the passage is possible only with a pneumatic boat but subsequently through trampling. The width of the water passage varies between 3.50 and 4.50 m. The maximum height of the gallery reaches 16 m. In the end of the gallery its height decreases and reaches 1.60 meters and further ended with a very narrow sump. The river passage connects with the middle and upper levels of the cave in several places. It is developed an average of about eight meters below both of them. The water level is richly decorated with formations (mainly stalactites) in its middle part.

The upper level (floor) has a length of about 135 meters. It is a high, dry and flat gallery. The width and varies from 7.50 to 11.80 meters. The height is also variable 8 -14 m. In the South end the height decreases and reaches 2.80 meters. The upper level ended with pit (8.80 m deep) with which it makes connection with the middle level (Big Hall). About 12-13 meters from the start of the upper passage in the left (in the direction of entry) there are two holes (gaps) through which it connects with the water level of the cave. Shortly before the end of this section, a well-shaped natural playground right of the gallery there are cave shrine .

The pit leads to the Great Hall respectively to the Middle level of the cave. It has dimensions of 63 x 69 m and has an area of about 435.2 m 2. The height varies between 11 and 14 meters. The hall is associated with underlying lower (active) floor of the cave in several places. Three of them are pit with depth of about 8 meters. Almost the entire surface of the hall is covered with keeled stones and boulders. The dripstone formations here are relatively small, except for the western periphery of the hall there is a great variety of formations - stalactites, stalagmites, draperies and so on.

In the southwest part of the Hall leads off two dry branches that conditionally could be named "Eastern" and "Western". Eastern branch has a length of about 180 meters. Its first part it is a dry, and flat with a width ranging from 5 to 12 meters and high on average about 6 meters. The floor is covered with stone blocks, and in the final part with clay. The secondary formations are relatively less.

Western branch is shorter (74 m). The width varies from 7 to 20 meters. The floor is identical as in the Eastern section (passage). In the end, western passage connects with the water level of the cave in two places.

The temperature in the cave is 21.8 °C at a relative humidity of 96%.

According to special studies (see the Chapter "Biospeleology) the cave is habitat of 10 species of bats between prevailing Miniopterus pusillus and Miniopterus fuliginosus.

The cave is mapped in the 6-8 November 2013 the Bulgarian-Chinese team composed Al.Zhalov, K.Danailov, K.Bonev, T.Markov, Tsv.Parov, Zhang Fang and Zhoug Chunshiu.