The Yangpu Ancient Salt Field is one of the most unusual historical sites on Hainan: a coastal shelf of volcanic rock carved into over a thousand individual salt-collection troughs, each one rimmed with a thin raised edge to contain the seawater that fills them at high tide. As the tide recedes and the sun works on the shallow pools, the water evaporates and leaves salt crystals in the stone — a technique that has been in continuous use here since approximately 800 AD, when salt workers from Fujian province relocated to the Yangpu Peninsula and adapted the volcanic rock shelf for their purposes.
The site sits on the Yangpu Peninsula, a few kilometres from the Yangpu Economic Development Zone that was established in 1992. The contrast between the industrial port infrastructure visible in the distance and the ancient salt-making practice on the shoreline below is startling. About 30 families still work the troughs using traditional methods; the salt produced is considered to have particular flavour qualities and is used in traditional Chinese medicine as well as local cooking. You can watch the collection process during low tide in the dry season (October to April), when evaporation rates are highest.