Gossigul Cave was designated as a Natural Monument on June 4, 1969, getting protection from the government for its educational and natural values. In 1974, the cave was opened to the public. The cave has various levels with underground water flowing on the bottom level. The cave is mostly made of limestone with various microorganisms inhabiting within.
Source: Korea Tourism Organization official English tourism database. Opening hours and details can change — check the official website before visiting.