The Gimnyeonggul Lava Tube (Korean: 김녕굴), located in Donggimnyeong-ri, Gujwa-eup, Jeju City, is one of the World Heritage Sites in South Korea.
The upper part of entrance is 12 m high and 4 m wide and is bent in a collapsed S shape.
Because very little organic material has infiltrated the tube, Gimnyeonggul does not offer favorable habitats for cave life.
The Gimnyeong lava tube is also called "Gimnyeongsagul" or "Sagul (Snake Cave)", a name originating in ancient history.
If people didn’t make that offering to it, it caused natural disasters such as typhoons.