From its entrance beside the NCO training camp, Andong Tunnel cuts through to Erchong Mountain, site of the island's army headquarters. From the entrance the tunnel slopes downward at a 30-degree angle along 464 steps that run for 641 meters. The tunnel was built during the cold war, in the 1970s. After the military released it in 2002, it was renovated by the Matsu National Scenic Area Administration and opened to the public in 2004. The restored scenic outlook, arsenal, military barracks, meeting hall, and pigsty in the tunnel have great value for tourism; and around April every year black-tailed gulls, black-napped terns, and other protected birds fly in from Japan to nest and reproduce around the mouth of the tunnel. From the scenic outlook you have a fine view of blue sea and azure sky, interesting rock formations, and flocks of soaring birds that attract crowds of bird-watchers every summer. ● Please:Turn on the lights as you enter the tunnel and turn them off as you leave. Vehicles are not allowed inside.