Simujigi Waterfall is a natural waterfall located beneath Gyubongam at 700 m above sea level. The water level rises during periods of heavy rainfall. Rock formations around the waterfall are composed of Mudeungsan tuff. The waterfall is 72 m high (lower part 35 m, mid part 15 m, upper part 32 m). The sliding fall is inclined at around 45 degrees until the mid section. The last 7 m of the fall is inclined at 90 degrees. As the only natural waterfall of Mudeungsan, Simujigi Waterfall is considered as an area of high scenic and geological value as the fall preserves pyroclastic deposits. The name of the waterfall derived from the word, ‘Saemujigae’ (three rainbows). It is said that three rainbows appear over the waterfall after the rain. Rainbows over the waterfall appear truly magnificent after the rain. The path leading to the waterfall was once occupied by wild ginseng diggers. The trail has been improved after it became known to ordinary hikers. Today, hikers can experience unexplored regions of Simujigi Waterfall in the primeval forest.