Nangan Beihai Tunnel

An underground boat harbour cut into granite in Nangan, Matsu, one of several small craft tunnels the army began digging in 1969 under the codename Beihai (北海), along with those on Beigan and Dongyin. Soldiers dug its grid of waterways, 640 meters long and 18 meters high, largely by hand and at the cost of several lives, but the large tidal range and typhoon damage soon after its completion in 1971 put it out of use. Reopened in 1990 and managed by the Matsu National Scenic Area (馬祖國家風景區) since 2000, it can only be entered according to a schedule of tides, and it makes for a scenic place to watch the bioluminescent plankton known as blue tears (藍眼淚).