The sour pork hash of Qu???ng Yên may be compared to other northern specialties of pounded pork products, but the species of shipworm in Qu???ng Yên can not to be found anywhere else but in the currents of the Chanh River.

The river flows directly into the sea; with a mix of fresh water from the plains and salt water from Ha Long Bay. The shipworms of the Chanh River are best when eaten in a sour soup, and can be caught during any season but the most interesting is in summer.