Third Tunnel of Aggression

Only 44 km (27 miles) from Seoul, the incomplete tunnel was discovered in October 1978 following the detection of an underground explosion in June 1978, apparently caused by the tunnellers who had progressed 435 metres (1,427 feet) under the south side of the Korean Demilitarized Zone (DMZ).

[2] It was apparently designed for a surprise attack on Seoul from North Korea, and could, according to visitor information in the tunnel, accommodate 30,000 men per hour along with light weaponry.

[5] North Korea then declared it part of a coal mine,[6] the tunnel having been blackened by construction explosions.

[9] Visitors enter either by walking down a long steep incline that starts in a lobby with a gift shop or via a rubber-tyred train that contains a driver at the front or the back (depending on the direction as there is only one set of rails) and padded seats facing forward and backwards in rows for up to three passengers each.

[11] The South Koreans have blocked the actual Military Demarcation Line in the tunnel with three concrete barricades.