Introduction to the Yalu River Estuary Wetland: The Yalu River Estuary Wetland is a national wetland nature reserve. Composed of reeds, tidal flats, swamps, and shallow sea areas, the Yalu River Estuary Wetland is extremely rich in plankton. Countless species of organisms survive in the vast shallow sea area. Fish, shrimp, crab, clams, etc. are all delicacies for the birds.