Seongnyugul Cave, a Natural Monument of Korea, is a limestone cave with a general northeast-southwest orientation. It has a total length of about 870 meters, of which only a strip of 270 meters is open to the public. Inside the cave are a variety of cave formations, including stalactites, stalagmites, columns, and cave pearls, which are commonly found in limestone caves. Unlike other limestone caves in Korea, Seongnyugul Cave has twisted columns and submerged stalagmites. Twisted columns are often broken in the middle due to earthquakes that occurred after the columns were formed. Submerged stalagmites are notable because stalagmites usually do not grow under water as they are made from droplets that fall from the ceiling. As such, stalagmites found underwater were submerged after they were created, indicating that they were created during the Ice Age, when the East Sea was lower than the present level.
(Credit: Gyeongbuk Donghaean Geopark)