Manjanggul Cave is a major lava tube of the ten that were formed by the lava from Geomun Oreum. The lava tube stretches for about 7,416 meters which makes it the fifteenth longest in the world. It is 23 meters in breadth and 30 meters in height. Ropy lava, lava stalactites, lava stalagmites, lava columns, lava flowstone, lava helictites, cave coral, lava roses, lava balls, lava bridges, lava shelves, and lava flow lines are well-preserved. There are three entrances to the cave. However, only one kilometer of the entrance No. 2 heading southward is open for tourists. At the end of the passageway of entrance No. 2, there is a 7.6 m high lava column that was formed when a large amount of lava spilled from the upper level down to the lower level. The interior of the column is empty. There is a possibility that gas may have escaped after the formation of the column. A study was conducted on Geomunoreum lava tube system including Manjanggul Cave. The study revealed that the lava flow from the crater formed Bengdwigul Cave, Utsanjeonggul Cave, Daerimdonggul Cave, Manjanggul Cave, Gimnyeonggul Cave, and Yongcheondonggul Cave respectively. The formation of extensive lava tubes as large as 15 kilometers long from a single oreum or parasitic volcano is very uncommon. Since the shape and topography inside the cave is well preserved, Manjanggul Cave is of high academic value.