A villager prepares straw at ancient salt fields on May 5, 2005 in Yantian Village on Hainan Island, China. The straw and bamboo mats will be used to filter dried tidewater mud and seawater in the process of creating thick brine which will be poured into troughs to be evaporated under the sun to make salt. Yantian is a small fishing village on the western coast of Hainan Island. Its ancient salt fields are more than 1,000 troughs chiseled out of volcanic rock. During the Tang Dynasty (618–907), villagers began to chisel volcanic rocks on the seashore. (Photo by China Photos/Getty Images)

Villagers collect salt from ancient salt fields on May 5, 2005 in Yantian Village on Hainan Island, China. (Photo by China Photos/Getty Images)

A villager prepares dried tidewater mud at ancient salt fields on May 5, 2005 in Yantian Village on Hainan Island, China. The dried tidewater mud will be placed with filters like straw and bamboo mats above a pond. The mud will then be soaked with seawater. After repeated treading on the mud, thick brine seeps into the pond below. Finally, the brine will be poured into troughs to be evaporated under the sun to make salt. (Photo by China Photos/Getty Images)