Estuary? Where a river flows into sea and it is hard to tell what is sea and what is river,
Its Something on a river
A watershed is an area of land where all water drains to a common point, such as a river, lake, or ocean. It includes all the rivers, streams, and tributaries that flow into this point. An estuary is a partially enclosed coastal body of water where freshwater from rivers and streams mixes with saltwater from the ocean. Estuaries are important ecosystems that provide habitats for a wide variety of plant and animal species, as well as serving as nursery grounds for many marine organisms. Together, watersheds and estuaries are interconnected systems that play a crucial role in maintaining water quality and supporting biodiversity.