The Yeoncheon Inverted Icicles are located on the railroad in an abandoned tunnel on the Gyeongwon Line. The tunnel was originally located on the Gyeongwon Line, which was connected to Wonsan, North Korea, but was abandoned in 1945 when the railroad was cut off. The fact that inverted icicles grow inside the tunnel became known by community residents in 2005. Hundreds of inverted icicles rise up from the bottom of the tunnel, which is 100 meters long and 10 meters wide, and they vary in size from small to large. They start to grow in mid-December and remain intact until March of the following year.

You may easily imagine icicles growing from the ends of eaves in winter, but as they grow from the bottom upwards, they have received extraordinary attention from academia. Recent studies have shown that inverted icicles are caused by two factors.

The first cause is that the icicles project upward as water from the tunnel roof drops continuously on the frozen surface of the ground. The second is that the fine water molecules on the surface of the ice on the ground cause the water molecules underground to rise up to grow the icicles. The water freezes on the ground due to the cold air of the atmosphere, but the underground is relatively warm, thus not allowing the water to freeze. The difference in temperature between the ground and underground causes the water underground to have more water molecules, and the difference in the relative thermomolecular energy from the ice on the ground results the underground water molecules moving towards the ground.

Yeoncheon Inverted Icicles are confirmed to grow both types, and visitors are able to see the combination of icicles growing from above and icicles rising from the ground.