The 2nd Tunnel, one of several excavated by North Korea for the purpose of infiltrating South Korea, was discovered in 1975. Spanning a total length of 3.5 kilometers, only 500 meters of the tunnel is accessible to civilians. To visit this site, visitors are required to book as part of the DMZ Peace Tours. Additionally, personal identification, such as a passport or Alien Registration Card (ARC), is necessary for access.