There is Ryongmun Cavern, a limestone cavern, in Kujang County, North Phyongan Province of the Democratic People’s Republic of Korea.
Known as an underground scenic site, it has been formed through karstification for a long passage of time.
A rare cavern in the world, it is 6 000m long. It consists of two main caves and multiple-sided holes with over 20 scenic spots unfolding a myriad of stalagmites.
