What is an area where river water mixes the ocean water?

An estuary is a coastal body of water with one or more rivers or streams flowing into it, and with a partially or fully open connection to the sea. Estuaries are formed where rivers meet the sea, and the seawater mixes with the freshwater from the river. The mixing of saltwater and freshwater creates a unique environment that supports a diverse range of plants and animals. Estuaries are also important for human activities such as fishing, shipping, and recreation.