The Doi Cave is created by natural erosion through thousands of years in the middle of a limestone mountain in Lung Sum hamlet, Dong Loan commune, Ha Lang district. 

Running 1000m deep into the mountain with an average height of 40m, the cave has three chambers and two storeys separated by stone walls and stone windows. 

The first opening has many layers of glistening stone reminding people of silver or golden waterfalls. The floor of the cave has many stalagmites in the form of cakes or pools of crystal water. 

In the second chamber, with a length of 200m, stalagmites stack up to form mountains with terraced rice fields, or fairy paddy fields as they are called by local residents, surrounded by clear water and hundreds of silver waterfalls. 

The third part of the cave has two storeys. The first storey is around 80m high with rocks in various shapes and sizes. 

The second storey has an average height of 60m, winding in the shape of a semi-circle. From the ceiling of the cave, stalactites hang down in harmony with rising stalagmites. 

Bright yellow stalagmites rise in the deepest part of the cave, looking like solid stone columns propping up the ceiling. 

With its magnificent beauty, the Doi Cave has attracted many local and international visitors. 

The cave is the second national relic site in Ha Lang district after the Stone Steles in Sung Phuc Pagoda was recognised in 1993. 

Cao Bang authorities pin their hopes on the Doi Cave, the Sung Phuc Pagoda and other beauty spots in the province such as the Ban Gioc Waterfall and Nguom Ngao Cave to draw more tourists to the province, thus promoting the social-economic development in the border areas.