Nangan Beihai (North Sea) Tunnel is a five-star tourist site. If you don't come here, you haven't been to Matsu! Beihai Tunnel runs from the Tieban Coast deep into the heart of the hills in a lattice shape. The tunnels water-channel section is 18 meters high, 10 meters wide, and 640 meters long. The depth of the water is eight meters at high tide and four meters at low tide. The tunnel path is 700 meters long and takes about 30 minutes to walk. The tunnel is big enough to accommodate more than 100 small landing crafts. Two divisions, three infantry battalions, one combat engineer battalion, and one dump truck company were mobilized to work day and night until the tunnel was completed, which took 820 working days. With the exception of a small amount of explosives, all of the work was done by hand; tunneling through the stone was arduous and dangerous work, and quite a number of the workers lost their lives. The tunnel is truly an achievement of almost supernatural proportions. During the time when the clouds of war enshrouded Matsu, the army tried using Beihai Tunnel as an underground wharf for supply boats. The shadow of those days remains, in the reflections of the vast stone walls that waver on the channel waters. ■Attention please: The tunnel may be entered only when the tides are favorable. Please note the tidal periods.