A stone anchor stock was discovered during the underwater archaeological investigation in Sai Kung waters in 2016. It is believed to have once belonged to a Song dynasty merchant vessel passing through Hong Kong. An anchor is a heavy object that was used to moor a ship to the sea bottom. This anchor stock is a component made of stone for either wooden or stone stock anchors. The shape of the anchor stock is similar to those that have been found in Hakata Bayin in Japan, Quanzhou in Fujian and the Nanhai No. 1 shipwreck in Guangdong. The size of the anchor stock is considerably smaller than the comparative examples listed. It was initially deduced to have belonged to a foreign trading vessel. Further research on the anchor stock needs to be undertaken. This significant discovery has provided very important data for further investigation of Song dynasty era maritime trade in Hong Kong.