North Korean soldiers dug the tunnel through granite rock using explosives and manual labor.
The discovery occurred after a defector provided intelligence regarding the location of the secret passage.
It is one of four known tunnels discovered by South Korean forces, though authorities suspect others remain undetected.
The tunnel was designed to allow 30,000 armed troops to pass through it per hour.
The tunnel crosses the Military Demarcation Line (MDL), reaching points deep within the Southern side of the DMZ.
The 'coal' found on the walls was confirmed to be applied by North Korean workers to deceive investigators.
The tunnel's air quality is monitored continuously for safety as it is located deep underground.
The Third Tunnel, also known as the Third Infiltration Tunnel, is a military passage discovered in 1978 that connects North and South Korea beneath the Demilitarized Zone. It spans approximately 1,635 meters in length, two meters in width, and two meters in height, designed to facilitate a surprise attack on Seoul. North Korean authorities originally attempted to disguise the site as a coal mine by painting the walls black, but South Korean investigators identified the geological inconsistencies. The tunnel is located roughly 44 kilometers from Seoul, making it the closest North Korean infiltration tunnel to the South Korean capital. Visitors traverse a steep, long, and narrow concrete slope to reach the tunnel's interior. Inside, the passage is divided by thick concrete blockades installed to prevent further unauthorized access from the North. The site serves as a physical reminder of the ongoing division of the Korean Peninsula.
The DMZ-themed sculpture and signage located in the outdoor plaza near the tunnel entrance.
Wear comfortable walking shoes with good grip, as the steep descent and ascent are physically demanding.
Use the provided rental lockers for large bags and bulky items before entering the tunnel.
Consider carrying a light jacket, as the underground temperature remains cool even in the heat of summer.
Do not attempt to touch the tunnel walls or venture past the designated metal railings or barricades.
Closed every Monday and on major national holidays.
Photography is strictly prohibited inside the tunnel; mandatory safety helmet must be worn at all times while underground.
