What Forms where a river ends and becomes a body of water such as a lake or an ocean?

When a river ends and flows into a larger body of water, such as a lake or ocean, it typically forms a delta or an estuary. A delta is characterized by the deposition of sediment as the river slows down and spreads out, creating landforms at its mouth. An estuary, on the other hand, is where freshwater from the river meets and mixes with saltwater from the ocean, creating a unique ecosystem. Both formations play crucial roles in biodiversity and serve as important habitats for various species.