Houao is a coastal rock formation area on Dongyin, part of the Matsu island group. Sea erosion has carved the shoreline into unusual shapes, making it a worthwhile short stop for travellers exploring the island's cliffs and military-era sights.
The appeal is simple: wave-cut rock, open sea, and a rougher edge of Matsu than the villages on the larger islands. It is best visited as part of a wider Dongyin loop rather than as a single-purpose trip from Nangan.