Hang Doi cave (also called Nguom Ca Khao in the local language) is situated in a mountain range which is 700m from public roads in Lung Run village, Dong Loan commune, Ha Lang district. Geographical coordinates X=678817; Y=2516647; entrance elevation: 600m asl. The cave is recognized as a national scenic spot pursuant to Decision No. 622/QD-BVHTTDL of March 10th 2014 of the MOCST.
Hang Doi cave is active with a total length of 1,134.1m. The ceiling is up to 40m high, and the chamber is 75m wide. The cave consists of several sections and up to 3 levels, with lots of speleothems e.g. stalagmites, stalactites, columns, rimstones, ponds and lakes of various shapes and sizes, including beautiful rounded accretions called “cave pearls”.
Hang Doi cave can become a major tourist attraction of Cao Bang Geopark in the very near future.
Plan view of Doi Cave
Doi cave is formed in 20-25cm-bedded limestone and siliceous limestone of Na Quan formation (D1-D2nq). The cave is oriented NE-SW at the starting section then turns to the NW-SE.
According to VIGMR, Doi cave is active, with a total length of 1,134.1m and a total area of 23,970m2 (excluding sinkholes). The ceiling is up to 40m high, and the chamber is 75m wide. The major sections are as follows:
The entrance section is 65m long and inclined at -16°. The cave floor is rather rough with big avalanche boulders interbedded with stalagmites. The cave wall is covered with many speleothems including rimstone and travertine.
The next section is about 150m long and horizontal. The cave floor is inclined at -5° and divided into 2-3 levels which are 20m apart, forming narrow parallel strips over a length of 50 meters. Beyond this, there are only two levels. The cave is wide with a high ceiling, which creates cool and refreshing feelings. The cave floor is flooded in clear and clean water. Immersed in the water is a variety of carbonate precipitation forms. High above in the second and third levels, stalagmites, rimstone, and travertine lines thrive. At the end of the cave, the second level oversteps the first level with a large travertine array, creating a grandiose and spectacular view.
Doi cave ends with lakes where it expands and turns to NW-SE. The second cave level also extends to form a large upper chamber (Figure, dark-colored part) with many beautiful speleothems – stalagmites, stone pillars, stalactites, and stone terraces. On the first floor, large travertine ponds are found throughout the cave floor, containing many beautiful rounded accretions called “cave pearls” or “Dragon eggs”. In the middle of the large chamber is a sinkhole.
The next section of the cave expands with a collapsed ceiling, and stone columns and avalanche boulders on the cave floor. The cave then narrows back to normal as at the entrance section with a flat floor, many stalagmites, rimstone, travertine lines and cave pearls before ending with a sinkhole about 15m in diameter.
Stalagmites and stalactites in Hang Doi Cave