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Artificially carved with divine craftsmanship

In 1968, as part of the strategic "Northern Sea Project," several "underground docks" were excavated in Maqiao (Matsu), exclusively for guerrilla warships. Following military release of the sites, these remarkable engineering feats have become a distinctive "battlefield landscape" in Matsu. Visiting Matsu without experiencing the Northern Sea Cave is like not having been to Matsu at all.

Located along Tieban Coastline, the Northern Sea Cave is a deep channel running through the mountains, forming an "H"-shaped waterway with a height of 18 meters, width of 10 meters, and length of 640 meters. During rising tides, the water level reaches 8 meters; during falling tides, it drops to 4 meters. The entire trail is 700 meters long, requiring about 30 minutes for a full loop, but entry is only permitted according to falling tide schedules.

This underground tunnel, capable of accommodating more than 100 small landing crafts, was considered a complex project in its time. The task assembled two divisions, three infantry battalions, one combat engineer battalion, and one dump truck company, organized into three groups that worked nonstop day and night over 820 working days. At that time, due to primitive construction equipment, dynamite blasting was used alongside manual labor to carve through granite rock walls with hammers and axes. Many soldiers sacrificed their lives for the project, making it a monumental achievement both in scale and difficulty, truly a marvel of divine craftsmanship.

In decades marked by war, the Northern Sea Cave was once intended to function as an underground logistics hub. Today, as visitors step into the deep tunnel, awe-inspiring rock walls and surreal reflections of floating shadows evoke spontaneous admiration from tourists.

Note: Visitor access is restricted to falling tide hours, please check tide schedules before visiting!

Nighttime Rowboat Tours to View Blue Tears
In recent years, the discovery of "blue tears" along with minimal light pollution at the cave’s entrance, has transformed the Northern Sea Cave into one of Nangang’s best spots for observing this natural phenomenon. Boarding a rowboat and slowly navigating into the cave, chasing glimmers of faint blue light, makes for an unforgettable experience.

Note: Blue tears are natural phenomena whose formation cannot be predicted. Flash photography is prohibited. For safety, no standing or seat changes are allowed during boating activities.