The river is one of the five types of water in Animal Crossing, the others being the ocean, the river pool, the pond and the waterfall. It stretches from the top of the town to the bottom. At the top is the waterfall, which feeds the river. The river passes through the town, going through the river pool and possibly splitting in two. There are usually 2 or 3 bridges.
River mouth
The river mouth is the acre where the river meets the ocean. Some towns have two. The Salmon and King Salmon can be caught here.