Nam Sang Wai is a preserved wetland in Yuen Long, a northwest suburb of Hong Kong. It is surrounded on all sides by "Kam Tin River" and "Shan Pui River". The rural development in 1990's forced most of the villagers to move to cities and made the fish ponds in Nam Sang Wai abandoned.

The only public transport in Nam Sang Wai is "Sampan", a small rowing boat that ferries the villagers across the Shan Pui River.

Nam Sang Wai also provides a good feeding habitat for migratory waterbirds such as Pintail and Black-faced Spoonbill in winter.