Here's why:

* Watery: Deltas are formed by the deposition of sediment carried by a river as it slows down and enters a larger body of water, like a lake or ocean. This creates a flat, low-lying area.

* Mouth of a river: Deltas are found at the point where a river meets its final destination.

* Land: The sediment deposited by the river builds up over time, forming new land.

Some famous examples of deltas include the Nile Delta, the Mississippi River Delta, and the Ganges Delta.