The Third Tunnel of Aggression is one of four known tunnels situated within the Demilitarized Zone (DMZ) separating North Korea and South Korea. Located more than 70 meters beneath the ground and at 265 meters long, the Third Tunnel of Aggression is a highlight of any DMZ tour.
The tunnel was built by North Korea in the 1970s, who initially denied its existence when South Korea discovered it later. The North were then said to have claimed it was a coal mine, before it was revealed that they had dug the tunnel in order to launch a surprise attack on Seoul. The South eventually took control of the tunnel, blocking off the demarcation line with the North via concrete barricades.
Although the Third Tunnel is now very much a tourist site (there’s even a gift shop near its entrance), it still remains guarded and taking photography is forbidden once inside. The tunnel passage is dark, long, and narrow, and it’s a steep incline to access it.
The DMZ can only be accessed via authorized shuttle buses and tours. There is also a dedicated monorail that serves the Third Tunnel area.