The term 'Mouth of a River' refers to the area where a river meets the sea. A DELTA is a landform created by the deposition of sediment at the mouth of a river, usually in the shape of a triangle. An ESTUARY is a partially enclosed body of water where fresh water from rivers and streams mixes with salt water from the ocean. INFLUX is the flow of water into an area, such as a river or lake. Outfall is the point where water flows out of an area, such as a river or lake. All of these terms are related to the mouth of a river, where the river meets the sea.